Point to Point vs Circuit Board

Simple circuits of tube amps invite point to point wiring, but for a solid state amp you would have wiring everywhere along with interference caused by all the wiring going everywhere, the routing would become too complex for sure.

Incorrect. A transistor has 3 pins, a tube typically has 6 to 9. A tube amp invites P2P wiring as the mechanics of an exposed tube in a socket on a chassis provide a layout.

SS products could be similarly designed with sockets on a backplane, but costs would be prohibitive. P2P is impractical for many of todays electronics with panel gewgaws and remote control.

PWB, first described in 1903, and transistors became popular about the same time in the 1960’s.

Point to point wiring is absolutely necessary for designers who cannot design a decent circuit board.  I was lucky.  My designer was a NASA rocket scientist who helped with both the moon landing (Apollo 5) and Voyager missions.  His circuit boards did not have "Thin" Crap.  Too many individual wires means too much noise.

Too many individual wires means too much noise.

Utter nonsense.

Bad layout, routing and impedance understanding cause devices to have low SNR, not the interconnect method.

Six of one, half a dozen of the other.  If the circuit board traces are thick there will be less resistance in the trace and therefore will not be energy thermal loss. 
Depending on design either can have capacitive and inductive reactances that can affect sound quality. Design is everything.
In tube amps having independant tube mounts that are bolted to a frame are much better than epoxy mounted soldered tube mounts. Epoxy boards over time get brittle by the high heat tubes radiate. Solder joints can loosen on the board as well. Point to point wiring normally will carry more current and have less loss.
With solid state production costs and assembly labor would be enormous and difficult because usually has many small components. Servicing point to point solid state would also be difficult. Can you imagine the mess of a home theater reciever with point to point?  If well done printed definately best for solid state. 

Blue circle amps were all point to point...
http://www.soundstagenetwork.com/revequip/bluecircle_bc208.htm