Because otherwise the Olympics for road cycling and actual high-level road cycling races become totally different things.
The entire game of road cycling races is based on judging these gaps. Without it, you would probably never let anyone ride off. Then races become attrition, followed by sprint.
Either that or you get a weird spotting system where people try to get gap timings to the riders through unofficial channels. Probably from the broadcast, but if delayed too much, from physical spotters with stopwatches.
I'm talking about the whole of cycling, not just the Olympics, so the first point doesn't stand.
Do you really prefer the spectacle of the peloton letting a breakaway head off into the distance, knowing that in 95% of cases they can just reel it back in just enough not to have an effect on the GC? Today just showed how exciting it is when people can head off down the road far enough for the others not to know what's going on. I think on balance I prefer attrition followed by sprint, although I'd contend that's a micharacterisation of what would actually happen.
Besides, isn't that exactly what the TDF used to be and what turned it into the best cycling race in the world? This year's TDF at least gave us a glimpse of what it could be like when someone rips up the rule book and the Sky train doesn't optimise the entire race into irrelevance.
I also think that there are enough cameras around to stop unofficial channels. And who's to say whether the person on the roadside is someone who's for you and giving you good information or against you and feeding you lies?
I think that you can do a lot against the 'optimized races' by giving riders the timing info reliably _without_ giving them radio communications with their teams.
I also think that currently, the races are actually quite fun. Even in the sky times in the TDF, there were breakaways with a chance, there were people who would solo to a victory.
I don't think unofficial channels are ever going to be policeable. Obfuscation is too potent. And I don't think it would be interesting if teams start competing to be better at getting their riders extra info. Even though I think its quite fun to try to design such systems.
A road race involves people traveling over dozens of kilometers, with many spectators lining the streets. There are so many ways a spectator can signal something to a rider in code (color of hat, waving or not waving a flag / choosing what flag, shouting something as they pass, etc.).
Sometimes a spectator might just say something about "oh that group a couple minutes before you looked fast" and not even be part of a team.
The entire game of road cycling races is based on judging these gaps. Without it, you would probably never let anyone ride off. Then races become attrition, followed by sprint.
Either that or you get a weird spotting system where people try to get gap timings to the riders through unofficial channels. Probably from the broadcast, but if delayed too much, from physical spotters with stopwatches.