Maybe the pubbers are playing FACEIT and trying to learn competitive and get better at it...?
The idea is that new players come into FACEIT and learn about the 6's format, grow interest in it, and join the competitive community after this whole baby stage of coming from pubs. Think of it like a competitive matchmaking if it was made by competent developers instead of a water cooler full of big pink cookies. Of course this has the caveat of bad players coming into the system and not knowing what they doing and some of them just completely being shit or stubborn. It's a roll of the die and a lot of it has to do with the high bar of entry for competitive TF2 compared to competitive CS:GO.
If you don't want to play with scrubs that are just playing their placement matches, that's the point of placement matches and the benefit of the premium leagues. If you purchase premium/supporter, you can queue in the premium leagues so you only queue up with and against people in that league. The problem with that is you have to get into that league from winning and you also have to purchase premium or supporter, though they're pretty cheap they're still fees.
FACEIT right now may seem like a bit of a cesspool like TF2C is, but the idea of supporting it now is that it will help TF2 in the long run. FACEIT is actually genuinely interested in supporting TF2 so we should be supporting back by using their website. Yes, FACEIT does have some genuine problems with their system and they've been looking into fixing their site and systems to appease players, but if you're going to shit on every company that tries to invest into TF2 because they're not as perfect as competitive circlejerks with high restrictions and incredibly competent players, then competitive TF2 is going to remain stagnant like it's been for the past 9 years.