It’s part of an ongoing process, for the last year or so, we’ve been gradually removing access from grandfathered in users who haven’t been active on the forum in a while and so this is just mopping up.
There are still quite a lot of people with fewer than 1000 posts who are very clearly only here for the MM. I spotted a grandfathered in member a couple of weeks ago who had made hundreds of posts in the last ten years but less than ten were outside the MM forums. Being blunt, they’re not members of the community, they don’t deserve access.
/edit - Sorry, I didn't specifically answer the second part of your question. There does seem to be a tendency for grandfathered in members to get more strikes and have more problem deals than other members. That doesn't mean that there's a lot of these generally but it's not uncommon to see a problem and realise it's with someone who was let in under the old system. By their very nature of non-involvement, it means they seem to care less for the community.