Thunderdome ruleset will be limiting this to maximum value 5 (thunderdome also allows cl_rollalpha).

Example from baresi of exploiting high values here

Would anyone have objections to this restriction being implemented in smackdown, qcon etc?

Even a value of 5 seems quite a strong effect, can see comparisons here

No objections, your honor. Sounds good.

As long as rollalpha is blocked, I'm fine. Let them have 360 then ...

Rollalpha capped to 3. Rollangle whatever you want.

The purpose is to get a hint of how your opponent if strafing, which you can get with low values, and also reduce the peek-a-boo-effect. To have your own screen tilt doesn´t seem to give any obvious advantages.