Doesn't it depend on what you mean by ticket? The airline "ticket" is the written (or electronic) documentation of the contract of carriage between the passenger and the airline. That contract can stipulate whatever both parties mutually agree on. It's always been the case at most airlines that the contract is non-transferable. There can't be anything objectionable in the contract including, for the relevant fares, provisions that the airline is never under an obligation to refund the fare paid, and never under an obligation to carry the passenger on any flight other than the one stated on the ticket.

Genuine "travel or bust" tickets (no changes, no refunds, ever) have been around for a long time outside the US and have never caused any legal problems, and I doubt they would cause any within the US either.

You might be interested to know that there are some tickets to sports and arts events which are non-transferable. For example, season tickets to a football club's matches can be non-transferable. Also, if you buy a ticket for the Bayreuth Festival, your name will be printed on it and the opera house may demand to see ID to ensure that only the named ticket-holder gets in.