I really appreciate the initiative in taking your time to make a post like this. I think having community conversations about things like this is super important, and echo what you say about getting others involved in this conversation as well. I can’t speak for the admin team as a whole before this discussion has been had in more depth, but I do want to give my personal thoughts on this topic.
On your first point: in principle, I totally agree. I don’t think class restriction patterns and paradigms are something that should change from season to season, or even, except in qualitatively different divisions, from division to division. I think, however, that it is the way it is right now because of certain edge cases that don’t fit neatly into the system you’ve proposed. I do agree with the idea of having general rules for who should be able to offclass, and in fact, there are such rules:
[1006.3.3] - Sandbagging and Class Restriction Guidelines
In general, we will class restrict:
If a person has made the top 3 in the same division
If a person has made playoffs in the division above
If a person is demonstrably better in a class than everyone else in a division
But the wording here is deliberate, even if a bit intentionally vague, and I don’t agree with putting in rules more set in stone. Consider, for example, the case of someone who has placed in a higher division, but is unable to find a team in that division because the skill range has shifted drastically (which I know past cases of - just don’t want to name them to avoid putting them on the spot). Consider the case of skill decay, where someone has played in higher divisions but is no longer as good, if because they haven’t played tf2 in a while or just because they stopped having as much time to devote to the upkeep of their skills. Consider players who want to play a division they’ve placed in before, but their teams get placed in a lower division because they aren’t good enough. Should all of them be restricted? These are some of the edge cases that lead the rule to be vague and only speak in generalities as opposed as to for every case.
I do have a minor nitpick with your proposed wording - top half of a division can be exceedingly big in larger divisions such as Main - playoffs or placement would be a better bar instead in my opinion. With that said, another reason I don’t agree with having clearer, more codified rules is because divisions are inconsistent with treatment. Newcomer, for example, has super strict guidelines: you cannot play Newcomer at all if you’re not new to comp, and you cannot be class restricted in Newcomer - you can either play the div or not play the div. Then, do you think restrictions in Amateur, a division meant for people to have a fair place to work on their skills, and Advanced, a division meant for people to prove themselves and prove that they’re Invite worthy, should follow the same guidelines? It makes sense, to me, for different divisions to have different ways restrictions are handled.
On your second point, I once again agree in principle but not totally in practice. It does make sense to me that, for example, a medic from a higher division may still be able to maincall in a lower division. I also do agree that all classes can have huge impacts on the game in their own ways, even less powerful classes. But again, we already take this into account. Players are routinely restricted from Engineer and Spy just as they are from classes like Demoman or Sniper, and even though the same is not true for Medic, players are still generally outright denied from playing certain divisions - usually, for example, placement Invite players cannot even play Medic in Main, just because they can’t roster in Main to begin with.
Your third point I agree with the most. I think that offclass teams generally don’t have much to contribute to healthy competition. If people want to offclass in lower divisions, I think that’s great and should be encouraged, but entire teams of higher division players offclassing is just a recipe for sandbagging.
The way I see it, players have different skill levels: class-specific skill, and game skill. When they offclass, the former may change but the latter does not. When you put enough offclassers together on a team, their average game skill is still at a higher division. So I like to think of it this way: a team belongs in the division its players’ average game skill is, irrespective of what classes they’re playing.