Same here. I buy a lot of games on other platforms (gog, steam), so I could see it positive: itch.io saves me lots of money at the moment, because as long as I don't know which games I already have, I won't buy anything of course.
It was the first time I used itch.io and I'm quite devastated how bad the support is. The problem is not new, and it does not only affect single users. (Well only those who don't flood the server with scripts, it is, maybe most bundle-buyers did in the meantime so noone cares about the rest anymore). Even a "add evenrything from this page to the library" on every page would be far better than the shit this platform presents at the moment, thats only 60 clicks, not >1000