Yes, I know about hashtags. I use them. albeit sparingly, as I think is appropriate, without making my posts #look #like #Ransom #notes. For example, I tag my photos with "#photography". What I won't do is label my "boring" posts, because I like to think that every one of them has the potential to be boring to someone.
Jebus, you over-sensitive snowflakes. If you don't like what someone posts, you have options. In ascending order:
Scroll past.
Unfollow.
Mute.
Block.
I happen to enjoy reading what Mr. Blaze posts; it's informative and interesting. On the other hand, I find pictures of other peoples' lunches incredibly boring, but I don't go asking them to stop posting or to put content-warnings or "boring" hashtags on them.