Unfortunately it's not possible at the moment for users. Maybe in the next release. I'd argue that it could solve a lot of problems is users could better curate the content they want to see or not see.

I run an instance that's not to everyone's taste and I'm worried that other admins will block is entirely if their users don't have a way to do so.

i don't know, but i have 2 alternative if it's not possible

1. never click "all"

2. if you don't have an exhaustive list of instances to block you might be able to find an instance that does block what you want

Same discussion is happening in another post, I just commented there summarizing the options: https://lemmy.world/comment/36886

But yeah, instance blocking is an instance-wide admin function. More details in my other comment.

Probably the best way would be to report insurance to admins.

Currently yes. If you wanted to be in full control of which instances you can see, then you will need to administrate your own instance.

Hopefully this will change in the future!

I actually opened a issue about this, give it a thumbs up, or even better contribute code, donate or post a bounty on rysolv to make it happen.