This has been discussed before and it is frustrating. Unfortunately there isn’t any way to put a cap on how many postings can be done in a day, and newcomers are just trying to get their photos into the gallery without understanding how it affects the main feed. I’m not sure how you could get that information to them without someone policing the site, and that tends to cause bad feelings all around.
I know I’m not leaving as many comments as I used to. I do scroll back as far as I can, but it takes a while and if you comment, you lose your place in the feed, and have to start over.