Like plenty of other people, I'm strict about soloing on the first playthrough, but not because of a "git gud" mentality. It's because 90% of the bosses are designed to be taken on solo, and summoning in my experience tends to bypass all the interesting design choices crafted into the boss encounter. Most bosses just get shredded with more than one player on the field, even with their boosted health and damage output.
Only some of the tough bosses in Bloodborne and DS3, most of which are in their DLCs, retain the tension and strategizing that comes with fighting them solo when you do choose to fight them with summoned players.
For a feature that's clearly meant to be part of the whole experience, I do wish the earlier games in the series accounted for it more during boss battles. I'm totally fine with it by design making the fights easier, because hey, everything's easier when you have someone to help, but seeing this big scary monster/armored warrior stand around not knowing which target to attack or just get staggered over and over doesn't feel like a fun encounter for me. I think it's possible to make summoning in boss battles an easier time without it also just completely trivializing them and exposing the limits of the AI.
But ultimately, I'm not too bothered by it. I know that plenty of people also find it fun and satsisfying to overwhelm a boss that's been giving them a lot of trouble by summoning, and for some, it's the only way for them to make progress and continue enjoying the rest of the game.