I can imagine a young dancer respecting the music and also wanting to do something challenging or new and intriguing, or show-offy, just like most young men want to do.
I have heard, through anecdotal accounts relayed to me (male dancers who have had conversations with milongueros) that the idea of the milongueros not showing off is a romanticized myth.
According to the guys I have talked to about this, the M's DID show off. Deliberately and frequently. In fact, much of how they developed their own personal styles and moves was specifically about one-upping each other and showing off to one another. And when they weren't showing off their own dancing, they were positioning their follower to show her body (and booty) off to their rivals.
Many of the M's had massive egos and the notion that they never showed off seems almost ludicrous.
However (and this is a
really BIG however) in the tango culture of their time, their desire to show off, and the way they developed their dancing towards that end, took them DEEPER into the music and promoted an
increasing level of connection to their partner as well as respect for other couples on the dance floor.
Personal music interpretation played a big part in what they were showing off.
Having the woman appear totally enamored of him (and
being enamored of him) was part of a milonguero's goal, not just so he could potentially take her home, but so his buddies would
see that he had won her over.(even if only for the length of the tanda)
No-one could impress other milongueros by being a rude boor to other dancers. It was totally contrary to the suave and sophisticated image they were trying to create of themselves.
Sadly in many (if not most) tango communities worldwide now, showing off does the
exact opposite. The show offs often pay LESS attention to the music and its nuances, and they often completely ignore the needs of their partner (and I'm not picking just on leaders here.. follower show-offs do it too) If they aren't concerned with connecting to the music or to the person they are dancing with, you can bet that they aren't too concerned about others on the dance floor either!
So the real difference is not whether the old-timers did or didn't show off in their youth (and even now as they are older) The difference is in what showing off meant for their dancing, and what exactly they were trying to show. For the milongueros. it actually improved and enhanced their dancing. For most tangueros/tangueras today, their dancing
suffers when trying to show off.