Hmmm… That explains a lot…it does though create some inconsistencies. I often use that to make a complete copy of a post on meta to port to my instance as it makes modifying a guide created here to reflect my community as how-to for posting etc .
A suggestion maybe add the component to Meta that allows copying full post to clipboard? I believe there is a Theme component for this.
I can appreciate the reasoning. But maybe even re add it to a drop down in the composer that can be enabled/disabled. As some have mentioned their communities use it.
Even if the team were to make it an optional TC for installing Blockquote.