As far as I know, no. You do need a place to stay however, right?
As you correctly mention, no official sources mention the requirement of a hotel booking. The relevant text from TIMATIC is given in this question and no hotel booking is mentioned. This well-informed blog does not mention it and neither does the FAQ of the Chinese embassy to Canada or this guy's trip report. He does mention however:
The agents at the airports know next to nothing about the 72-hour visa-free transit rule.
And I've come to make similar experiences. Stand your ground, ask for a supervisor or read the rules on their screen with them if necessary.
However you do have to stay somewhere when in China and you do have to put down an address on your arrival card at immigration. This could be any address but I wouldn't just make one up.
Also remember you have to register within 24h, which is done by the hotel if you stay there, or if you stay with a friend they have to go to the police station to register you (even though I know of a lot of couchsurfers/airbnb hosts skipping this step).
(Finally, it is not a "72 hour transit visa" but a "transit without visa".)