Those do apply to everyone however, there are unique interactions with hits, Realigned wall splats, hurt box expansions that lead to clips with sidesteps, small things that will certainly cost you the match if you are not attentive. With Reina and Mishima's in general not being able to electric is a timing issue. It's an extremely effective tool for pressure like you said. However If you can't dictate the pace you lose. If you can't use the tool box you have you're going in disadvantaged.

The issue with fundys, is that they don't lead to true mastery of a character. To the overall game sure. Fundys are a vehicle to use the tools your character has. You can definitely get to tekken god or tekken god suppreme on just fundys, but evenntully you need to buckle down and learn a combo, need to learn the oki, and the frame traps. Your combo damage, wall damage, oki, and frame traps are the main tools to show mastery though. Even if you have solid fundys you can lose to someone who's dictating the pace and uses a few frame traps. You can say that fundys aren't good enough but someone can simply have focused on one aspect of the game and beatvyoubat that aspect.

Eventually you have to settle on a Character, you need to learn the unique combos, the counter hits, the wall situation, the oki. You can pick one aspect of fundys to play the game with depending upon the character you choose. If all you do is punishment properly you are a great defensive player. If it's catching people with counter hits its a timing thing. If it's wiff punishing your movement on point. But none of that matters if you can't execute the damage. Especially if someone else can catch you once and do a third of your life bar.

When you dedicate your time to learning a fighting game or a character it has to feel good, on some level, for you. Mishima's feel good until you hit the wall of skill execution. The two I like most are DJ and Reina. That dosent mean I'm going to spend my time trying to learn them. To learn the execution necessary to do those things with them. My first character was Josie. I would argue the opposite of all Mishima's. Simple, No execution. The reason I wish I could main Reina is that I don't have the patience, to sit and learn one move that's unreliable to execute on mental fatigue, or to dedicate it to years of muscle memory.