Workflows. When people get used to using a UX. It is very disorienting to learn new procedures to accomplish something you already have learned and used repeatedly.
Look at MS Word for example. When they first started to mess with the interface to “make workflows easier” it is met with a lot of upset…that they put fallback modes in.
I often use it to copy an entire post for example on meta here to make a copy on my forum for use of how-to docs. Ie the Creating Polls guide. Then either go back and copy paste the pictures (lazy method) or create new SS.
Removing that ability does makes it much more tedious then a block quite. Now on meta of course I don’t commit the reply to publish. As the intent is to just make a full copy.
There is I believe a copy post Theme component but that won’t work necessarily well for forums that are accustomed to using Blockquote.
I would recommend with any drastic changes similar to this one to have a Theme component that can be used to patch the function back in. Similar to what the team did with Category styles when they decided to have one core style. They made a TC still have the optional other styles available.
Something like the above enabled here might be good with a modified version to restore the og Blockquote for communities that prefer it.