The history of etiquette in cycling is pretty chequered. Even in epochs and circumstances where there existed a general expectation to stop, it was flaunted often enough to make the trend debatable.
Mechanical problems are extremely common nowadays, with electric derailleurs that can’t be trusted to last a stage, ultra-fast tyres that puncture more often in 200 km of beautiful tarmac than my tyres do in 1000 km of Paris streets, etc.
There should be a cost to these choices of equipment, notionally chosen as they are for marginal gains. Likewise, there should be a cost to falling off on a corner while others don’t, botching a shift, or getting sick. It’s a race! Own your decisions and race.
Waiting is not even good sportsmanship if it’s expected. It is this expectation (especially by the victim, e.g. Froome yesterday) that frustrates the race, not the act of sometimes waiting, which might indeed be good sportsmanship if the expectation didn’t exist.