Most other blogging and micro-blogging softwares (Wordpress, Twitter, Bluesky, etc.) allow you to turn off replies for particular posts.
It really helps with dogpiles, a LOT.
Mastodon is on board with quote-posts, but not the ability to restrict who can reply to your posts: https://joinmastodon.org/roadmap
If you think this is a feature worth considering, please leave a comment on this feature request on the official Mastodon Github issue list: https://github.com/mastodon/mastodon/issues/8565
The feature request is nearly 6 years old, and the third most 👍ed issue on the list. So add your 👍 to the top post while you're there. :D