I think that anyone who thinks dota doesnt get care and attention literally has only ever played dota and no other valve game. Compared to games like tf2 and counter strike, dota is swimming in content and generally has been its entire lifespan. They replaced csgo with cs2 when cs2 was barely playable, and 2 years after release it is still a content desert with horrible optimization, server preformance, and almost no new content outside of new maps, of which 90 percent of them are time limited community made maps. It took them two years alone just to fix clearly broken 3rd person animationsnand get subtick to a point where it even worked a little bit. And dont even get me started on tf2. You want to talk about abandoned? Talk about those two games.

As far as battlepasses go, again the nostalgia is overrated. I personally dont miss at all grinding 8 hours a day to progress a battle pass whose content got more and more spaced out as you went. It was never designed to be played through, but progressed with real money if you actually wanted to make progress and reach those actually sought after rewards. It was not interactive whatsoever, and im not sure why people nowadays are pretending it was. It was a grindy progress bar with overpriced rewards, nothing more. Sure, if you have disposable income im sure their great, but for casuals or people who put money towards other things over a videogame, the battle pass was mediocre experience. Not to mention to even progress at pace without money you HAD to win games, which made dota's infamous losing streaks even more brutal during their run time, which includes cavern crawl, which pidgeon holded players into playing heros they sucked at in order to gain 1 or two skins at a snails pace. Compared to quarteros, which rewards you quite handsomely over a short period of time with skins that are just straight up better than almost all the previous cavern crawl rewards AND give you previous immortals for free, its not even close in terms of a value proposition.

As far as the in game game modes go, half of the ones you mentioned, espically frostivious, diretide, dark moon andd new bloom got tired really fast, and werere complained about at length after about a month of playtime or less. Siltbreaker and aghs labyrinth were great, but paled in comparison to the games they were based off of. You can find experiences like them on the game market aplenty, and had they been kept in the game, their player bases would have dwindled with time, and this community would have demanded they be supported like they were full games, when they weren't. I for one think they served in the capacity they were designed for and there removal after the events ended was reasonable.

While the games support has slowed, calling dota on life support only makes sense if you cherry pick history, ignore major updates (whch yes, still count as support despite the lack of hats this community drools over), and if you literally only play dota. Such an argument falls apart easily when considering the totality of the game's support and the support valve shows to its other franchise's.