In my opinion, this would segregate the community unfairly and prevent people who want to teach newer players and play with lower level friends from doing so. Consider the veteran player who buys a copy of the game for a friend and wants to play with them. Under your plan, it forces the vet into a vet lobby, and the new player is blocked from vet lobbies. The new player quits in frustration because they can't play with their friend, and the vet gets annoyed that mechanics prevented them from playing together.
Also, level means nothing in terms of skill. It merely denotes experience. If a level 20 engineer, who has done nothing but spanner/ext/chem and heatsink ammo "because it works" (I'm sure we all have stories like this) is forced into vet lobbies, it'll merely kick the can for 20 levels, not solve the core problem of the pub stack itself.
I've agreed with you many times that stacks against newbies are bad for this game, but I disagree with that solution and offer a counter: Force premades with more than a certain percentage of vets on it (for argument's sake right now, let's say more than 1 per ship) into vet lobbies, and then force custom lobbies with that same certain percentage of vets in it before hitting the recruit from queue button into vet lobbies to close a loophole. Also, block vets from stacking a single ship (must maintain the 1 vet per ship rule) after the recruit button is hit to close another loophole. Solo queue, custom lobbies that don't recruit from queue, and Alliance PvE are excluded from this.
If this were to happen, here's what I'd expect to be the in-game response:
+ Custom lobbies would become the norm amongst vets, and less novice and casual players would be forced into stacks.
+ Clans as a means of social interaction, teaching the game, playing the game together, etc would get a slight boost, as a result of the above point.
+ Global chat and interaction amongst players would increase to fill custom lobbies. Most of us are social anyway. Might as well put it to good use, right?
+ Solo queue players would be less likely to be stomped, as it eases the burden on matchmaker.
- Some unsocial clans or clans/premades without many contacts would get frustrated with their newfound inability to find lobbies, or perhaps become the new inefficiency of this matchmaker and be the new stomp target.
- Communicating the 1 vet per ship rule to casual veteran players who don't read patch notes could be a problem.
- Part of the community would have to be educated in regards to custom lobbies.
- It would further hinder movement in pub lobbies.
Edit: I forgot one other idea in conjunction with this: reduce the base lobby timer to 3 minutes, with only one 30 second "add time" per team.