Question on small bass drivers in tower speakers

I noticed that many speaker manufacturers have been offering tower speakers with a multiple array of smaller bass drivers in their latest designs. I understand that having a series of smaller bass drivers in a cabinet can provide very fast and accurate bass response but I often wonder how these smaller drivers fair when it comes to reproducing the lower registers of the frequency range at louder volume levels (95+db).

I've seen claims of bass response down to the low 20hz range using two 6.5" woofers from some manufacturers like Proac as an example.

My question is this, how can these small drivers be capable of reproducing such low frequency when stuffed into a box when if you look at the manufacturer website of the speaker drivers themselves and see a listed Frequency response that shows the woofer only being able to play down to 40hz at best when taking a speaker of no more then 7" in diameter into consideration?

If someone was in the market for an almost "Full Range" speaker how likely are they to be happy with a tower that only uses 6.5-7" drivers at most that claim low 20hz capabilities verses some other manufacturer who uses 8" or larger drivers with similar advertised capabilities?

Even if I take into consideration the most inert cabinet designs available for these small drivers I still find it difficult to grasp the idea that they will be able to play bass that low on the scale with any real authority.

Please add your thoughts and experiences with small driver tower speakers and if you were impressed or disappointed with their capabilities of playing low and loud despite the advertised claims ..Thanks