Based on data from https://fedipact.veganism.social/ it seems that the majority of instances blocks threads.net. I’m sure there’s Lemmy instances with either approach that have slipped through the cracks as the list is a work in progress.
The percentage of users doesn’t correlate to instances as the biggest instance on the Lemmyverse has roughly 3x the users of the second largest, a NSFW instance, 4x the users of the biggest “niché” instance and 5x the users of what I see as the second largest general purpose instance.
That is pretty awesome, yes. But they most definitely were not kicked off the platform. I’m sure they had similar pushback when they first started all their other social media accounts but they persevered. Threads has gone quieter since its initial launch but it in no way is dying and once Meta turn their attention to it, it’ll liven up again and when it does I have no doubt those groups will pop back up too.
And they are far from the only group on there. Steve Bannon runs a Threads account for example called the War Room I believe.
This article will, I think, give you a fuller picture of Meta and why it cannot be trusted.