Because SpaceX is known to over-promise and under-deliver? They seem to have an extremely powerful institutional engineering capability. That's not fanboy talk e.g., we're going to mars! Just look at what they've accomplished. Landing a rocket on its business end is no mean feat -- for any engineering team, ever.
I know this is a YC forum but seeing the Astranis team's responses to people asking very incisive questions is troubling. Maybe they're far better at engineering than building confidence but I detect that sort of single minded dismissal (often of objective reality) that plagues a lot of entrepreneurs.
Maybe this is unfair but it sounds like someone got latched onto the idea of "micro-satellites" and won't let it go, ending up with "we can conceivably put up only X, so they'd have to be geosynchronous". Maybe there's a reason SpaceX is doing a LEO constellation, regardless of their unfair advantages in that regard.
Of course latency is an issue. Engineers will run away. Maybe you don't need them to succeed, maybe they are 0.1% of the market. Of course, where would Apple be without software engineer and designer buy in? Maybe the average customer shouldn't care, 'cause they're all high latency ok. Doesn't stop them from being swayed by marketing. A single infographic showing why low latency is better -- all else being equal -- what are customers going to choose?
Not sure why YC would have invested in this other than to broaden their portfolio. The chances of this company becoming a unicorn must be vanishingly small. If unicorns are no longer the VC mantra, cool, I've got a lifestyle business you can throw money at, provided there are zero expectations.
By all means prove me wrong and best of luck to you. Take this is as constructive criticism. If you're going to engage anyone in public bring your A game.