If what you've seen comes from r/pathfinder2e on Reddit, it's likely because the place is a borderline echo chamber nowadays, and will happily swear that everything short of dumping your key stat is viable regardless of whether it actually is or not.
You'll have a hard time finding any mention of something in the system being "not as good as the rest", or, god forbid, the system having specific shortcomings (you might see "the game has shortcomings" but specific mentions will be absent).
I really invite you to check multiple posts and look intently for those less positive outlooks, you won't find many and those you will find are likely to be at the bottom, on the other hand, you'll see a ton of echoed opinions about the absolute superiority of pathfinder 2 math, game design, class balance, etc... either over other popular system or in absolute.
I don't think the moderation team there is complicit, but it absolutely has let it go to shit over the years
TL;DR: to answer more specifically to "What is it that makes people really like summoning in general?" pf2e Redditors like everything about the system whether it's good or not