I do not see that as impossible. Power line decoupling is probably the most critical but should be doable.
A logical issue is of course that when you have put the TPA3116 or TPA3255 on the PCB as SMT component, why would you then swap to "through-hole" for the rest?
Welllll.... I'm not sure. One thought was easier servicing and then these old eyes aren't getting any better... Mostly it's a curiosity question.
We the DIY'ers are just a small splinter in the finger of the general consumption. Also I prefer working with through-hole components. SMT-repair is possible with the appropriate gear and good magnifying goggles such as used by dentists.
This was before you could find them for $6 to $10 on Aliexpress or eBay.
With SMT you need the right tools - for repair a hot-air rework station is a requirement, replacing components is then straightforward (you have to be more patient though). Once a components heated up you remove with tweezers and place in the new one - usually there's enough old solder, all you need is a bit more rosin to flow it. Ceramic tipped tweezers are great BTW, never seem to wear out, handle high temperatures, never get magnetized, tough as metal it seems.I've done some very limited SMT work. While building the board is relatively easy as you point out, I certainly didn't enjoy being the poor schmuck who had to fix one.