Sure.
If you check my season 7 stats, I've played around 2k games approximately.
I play on average, 10 games a day.
Suffice it to say, I've played/play more than any other player both in bronze/silver (where the majority of the player base reside) this season and on a daily average.
I can readily affirm that in every other game (so let's say 5 out of 10 games per day), at least one player is 'guilty' of doing what I said in the OP. This is an average; sometimes it might be more often, sometimes a bit less often.
That's a lot of players. I can also verify this with providing you my replays -- I do believe they include chat logs?
If you want to verify for yourself, go into a bronze/silver game right now (in ranked).
Pick something a little different, let's say.... Ashe mid.
Try to win, but make sure you end up doing poorly. Let's say... 1-7.
I guarantee someone on your team will call for reports on you for "int feeding" and/or "trolling".
P.S. majority starts at 51% percent, not 95%.
My point is: it's still a systemic issue that Riot has not clearly addressed to their entire player base; only to a few here on the forums -- and even then, still not very clearly addressed.
The problem is players below plat/diamond, just don't play that often. They're not aware of all the rules and regulations and changes to said rules. Riot doesn't make a very strong attempt or effort to make these rules or guidelines super clear (i.e. linking to them from directly within the client via a tab); they post some stuff here on the forums, where only a small percentage of players visit and check regularly.