Why is there a 3v3 blind mode?

I made a post about bots in 3v3 a few years ago. Lets say fast forward 3 years to 2017. I join one 3v3 blind mode for fun, and of course bots still on my team. I understand the ranked 3v3, but why even bother keep a mode that is honestly infiltrated by spam bots. Is Riot getting paid by these third party companies to keep 3v3 open so they can boost accounts? Honestly I see no reason even having this mode anymore. Its almost a guarantee there will be at least one bot in the game, and they only way to truly avoid one on your own team is to queue as a full premade, hence why ranked is still playable. I very rarely play 3s anymore so I'm not to stressed about it, but when I first started playing league 4-5 years ago I loved 3's for the quick games and the action packed pace of it. Now it feels like the experience is long gone for those who still play 3's on a regular basis. Either way, it seems as if 3's is just a lost cause, bot farming mode.