I agree with you, absolutely, but I also have tired of hearing this lecture, repeatedly, on the various groups because it doesn't change anything. I have to believe that moderators on groups.io have the same capability that moderators on most forums do and can split threads, move various posts to the threads they've just created by the split, and retitle those new threads.
Please, please, please start asking moderators to do this, because that does create value for future searchers and gets the point across when a certain someone or someones suddenly find their tangents, which are often valuable in their own right, suddenly in new and appropriately titled threads, preferably with a note that it was necessary to split it because it broke topic continuity.
The lectures do not and will not work. I've been around this block way too many times to say anything otherwise. If you have these powers please use them; if you don't then please ask for them.
I worry a lot. . . I worry that no matter how cynical you become it's never enough to keep up.
~ Trudy, in Jane Wagner's "Search for Signs of Intelligent Life in the Universe"