The only advantage to the moon is less DeltaV and travel time required.
The moon is actually a much harder place to have a long term base than Mars. With the moon you either get cooked for ~2 weeks and then freeze for ~2 weeks or you set down at the poles and constantly freeze. The Apollo missions where timed to get out before things got hot. The Mars atmosphere is thin, but provides ready access to nitrogen, oxygen, and carbon plus tiny trace amounts of hydrogen and even some noble gasses. The Moon is just shy of vacuum and would be very difficult to extract significant quantities of anything useful.
So going to the moon first means solving all sorts of problems than don’t help a Mars mission.
I'm not certain I agree with you about the only advantages: the moon also has the advantage of being much closer for emergency supply and rescue missions.
The Moon is very near and it's still possible to have near real time communication with it.
Going to the Moon helps learning about and solving many problems that will help on Mars for much cheaper and without incurring months and months of space travel.
Show me people living on the Moon permanently then we can discuss trying that on Mars. Otherwise it is indeed just for the show like the Moon landings.
The optimal place for a Moon base is likely one of the permanently lit parts near the poles, which are thought to stay at a fairly constant -50 C or so.
For comparison, the average surface temperature on Mars is -60 C.
The longest lit places we know of are lit ~94% of the year but then experience even longer periods of deep freeze. They also don’t get much sunlight, and having a base there would create a long shadow. https://linkinghub.elsevier.com/retrieve/pii/S00191035100013...
Multi month moon bases could be an intermediary before going to the moon, but those spots still get really cold.
The moon is actually a much harder place to have a long term base than Mars. With the moon you either get cooked for ~2 weeks and then freeze for ~2 weeks or you set down at the poles and constantly freeze. The Apollo missions where timed to get out before things got hot. The Mars atmosphere is thin, but provides ready access to nitrogen, oxygen, and carbon plus tiny trace amounts of hydrogen and even some noble gasses. The Moon is just shy of vacuum and would be very difficult to extract significant quantities of anything useful.
So going to the moon first means solving all sorts of problems than don’t help a Mars mission.