There’s point in both of these statements in my opinion.
On one hand, ranked =/= competitive. It just isn’t and wasn’t, even when we had mix of 5premades included in the chaos. So to get one starting DirtyBomber into more thoughtful games, ranked is lower threshold entry to 5v5 mode, with FriendlyFire and collision included. As an added bonus it should have some sort of mercenary limit system (or encouraging via class icons & reminders for missing class roles or similar) as it’s vastly used it tournaments. So getting into such mode earlier is generally good, as game is and hopefully will be advertised and balanced as competitive.
On the other hand though, there are tons of even higher than lvl7 people who are stunningly oblivious of even the most crucial mechanics of the game, like how objective repairing/defusing works (stacking being no-good and priority mercenaries). While sure, properly done matchmaker would technically put all these low-lvl-bot- like people playing together (ever seen CS:GO silver plays? quality fun), it doesn’t manage to do that now and even if it did, it wouldn’t be exactly enjoyable in the long run. Mechanics would still remain alien to these people, as if 6v6 and bigger pubs don’t really teach these things, even less will 5v5 do. What does teach these things however, is welcoming community AND proper damn tutorial.
Best of both words and a little TL;DC? Giving new players a proper start at the beginning of their DB “career”, introducing to basic mechanics in meaningful and easy-to-grasp- way, would ease a huge amount of frustration later on. And it would be allright to have them start ranked somewhat soonish.