It is to some measure an existing problem (though there are a lot of ways to contribute which are nearly 1005 uncontroversial, especially in more minor spaces - Wikidata, Wikitravel, Wikisource, Wikiversity, etc.) but it's definitely not the problem that the comment author describes. He didn't try to clean up anything. He didn't meet any adversity in doing so. He didn't try to pick up the trash. He threw the trash there and complained why other people - which are volunteers - are so lazy as not to promptly clean it up.
That sounds very noble but imagine every time you lifted a bit of litter you had to argue with someone about why it should be put in the bin. Sometimes even when you win the argument they take it out of the bin and throw it down again.
That's how many qualified-to-contribute people feel about Wikipedia now. I run all my web searches with '-wikipedia' as I lack any confidence in its pages. But that's only half the battle, it doesn't address people who arrive on topic-specific fora with statements like 'Wikipedia says that..'