is there a reason to split all uses out into individual issues?
No, there is ...

is there a reason to split all uses out into individual issues?

No, there is no special reason to report it individually. I found this tag in different files, so reported it to the respective module. If this is not the correct way, we can report it into one, and close other ones.

Actually, on further reflection on #5, it would be helpful if there was a meta to state the problem clearly, provide background (for example, deprecated by who), and to agree on a plan.

Actually, I found a list of deprecated tags in HTML5 and I reported the issue here.

Here is the list of all deprecated tags in HTML5.
https://www.tutorialspoint.com/html5/html5_deprecated_tags.htm

If this doesn't answer your question then we can close this issue. thanks.