Actually the woofer size and the box size will give you really important clues unless you command the force to defeat the physics.
Clue but not conclusion. SPL at a given frequency is surface area but also x-max but also the nature of the box itself (all of which are tied to power). Ports, transmission lines, horns (folded and otherwise), waveguides, passive radiators, room interactions. There are a *ton* of factors involved in the capability of a speaker to deliver SPL, and even more in the FR curves of that.
So, as I said before, you can't judge purely on woofer size. Nor even size + count (because arrays are a thing). You really have to look at the whole thing (or the graphed data); including and especially the actual SPL load.
Tell you what. I'll tell you the size of one of my drivers and you tell me what the max SPL at 60Hz is for the speaker (box and driver) is assuming I have only that driver in the box.
The speaker is 10". What's my max SPL at 60Hz according to "physics".
Not really sure who is in the realm of whatever and that outputting whatever from mains is a bad idea? Probably a more consistent response is needed and few graphs to support it?
I don't think that sentence can be parsed.
You seem to be alluding to an ignorance around sub placement in rooms and the auditory factors that influence it. Is that what you were trying to reference?
You keep mentioning physics in your post: but you've not put up a single formula in support. Do you think saying "because physics" is actually an argument?