-Expo wrote:
If they had been taken out of Scratch 3.0, ST must of had a reason for it. A reason that probably looks a lot like these:

1. It has an easy workaround

2. It was virtually unused

3. it was too complicated

I hope that helped

That is not why, it is mostly because the blocks were replaced (other than that, because the blocks were in removed extensions), and all at once was removed before 2.0 finished.
Also, days since 2000, video blocks, switch backdrop to () and wait, next costume/backdrop, and other “virtually unused” or “easy workaround” blocks still exist.
Edit: Actually, there was also this block (which was hidden but was in a currently existing extension)
https://en.scratch-wiki.info/wiki/Play_Note_()_for_()_Seconds_(block)
And yeah, that was the real reason it was hidden.