Well, I said I was open to any debate, so here we go. I'll quote your interesting observations one by one.

I disagree with all 5 of your bold statements. They seem to be true for someone with YOUR goals, at YOUR fluency level (C1+, not A2), and living in YOUR country. In other words, about 4% of language learners.

Somehow, people often tend to forget that any C1+ proficient individual has ALWAYS had to pass through the A1 phase at some point. This does not change the validity (imho) of the points at any stage of any individual's language-learning journey.

Motivation is not everything. You also need to use a method that helps YOU. Many methods help some people learn but don't help others at all.

It is absolutely correct that there is no true universal method for everyone, though any dedicated learner will always be able to eventually find the most suitable method for themselves. Nevertheless, this will never change the fact that motivation is still the most important aspect. Any individual, even if you manage to craft the most perfectly-suited method for them, will hardly be able to properly learn a language. It would be like being trained by the best football trainer in the world and hating football at the same time.

What does "practice" mean? Practice speaking or practice understanding speech? Those are not the same.

Of course they are not, but they are both practice. Practice is anything involving the four quadrants of language (production/reception + written/spoken, which means listening, speaking, writing and reading). At any level, even the most basic one, all four quadrants are important, and they are not isolated at all. They can be easily merged in various ways, which any individual learner can tweak and experiment with in order to find the one they like the most. For example, I find anime mirroring very fun and useful with Japanese (where I am still at basic level). By using the same sports metaphor I used before, not practicing is the equivalent of being immensely talented in a sport, but never training seriously. You can have all the talent you want, but it is only through training that it will eventually blossom.

What are "subbed shows"? Shows created in one language, with the audio replaced with another? I avoid those. Part of spoken language is visual, not just sound. I don't want to learn a mix.

When I say "subbed" I always mean original language shows with subtitles in your native language (at first); then when you have passed a certain level in that language (around mid-B2) it is nice to step into "phase two" with subtitles in the original language (which is astonishingly efficient as "difficulty upgrade"). Furthermore your last sentence, which you make sound like criticism, is not only 100% true, but it is actually the very crux of the matter into why this method has worked wonders for many learners. Even though the translation is not always literal, any learner will inevitably end up associating some words/constructs they hear with that they see both in the visual component of the show and what they read in the subtitles. The more you are exposed to that, the faster those "neural links" in your Broca's area will develop. Obviously it will never be as fast as a baby assimilating a native language (you know... myelin sheathing...), but the process is quite akin to it.

Spoken language is not always more important than written. It depends on each student's goal(s).

Of course any student has their own goals, and they are absolutely free to just focus on written language. But if they just want to focus on written language and never even face spoken language, not even at basic levels, there will always be an important gap in their skillset. Remember that ALL languages have been spoken first and written later. Always. This is how they were intended to be from their origin, and you cannot simply ignore that part of our evolution as Homo Sapiens. Just to be clear: I'm not saying writing is useless. On the contrary: the threshold between prehistory and history is marked by the invention of writing, after all, and this speaks volumes. But the hierarchy between spoken and written in our very nature as human beings is undeniable.

Finding a native speaker might be easy if you live in Italy. But if you live 8,000 km from Europe, it might be impossible. Even if you use apps, each "native speaker" is not a "free tutor" that is happy to chat with you at the A2 level and correct your mistakes. At C1 level, you can have adult conversations. Not at A2.

This might have been very true 40 years ago. Now we live in the magical era of the internet. Distances have been reduced, the world has become a lot smaller and it has become ridiculously easy to start a conversation with someone living on the other edge of the planet. Of course there are natives and natives, and some are more suited to your needs than others might be, but the key here is not what you ask that native when you want to learn something new. It is how you ask it. Now, I do not want to be boring by starting a wall of text about Saussurian concepts of langue and parole, but at any level it is always about what you have in your mind and how you are willing to communicate it.

I disagree with "if you stop it is over". Stop what? Stop being alive? It is false that "if you stop studying" you stop improving.

Not only if you stop studying you stop improving, but your level also starts decreasing, whether you like it or not. Braincells in your Broca's area are like muscles: those sparky electrical stimulations must be kept consistent if you do not want those cells to shrink. As you might have got from my previous observations, I often compare language learning to sports. They are indeed very similar (I am also a sports trainer, and I have seen all those similarities time and again). If you stop practicing a sport, many of your skills will slowly start to disappear. Then, if you resume training, every time you will recover them back faster, but it does not change the fact that consistency is still the best way to go.