This is exactly why. Some numbers:
- Polycarbonate thermal expansion coefficient - 65 * 10^-6 per degree C (source)
- Glass thermal expansion coefficient - 9 * 10^-6 per degree C (source)
Most amateur telescopes are used shortly after dusk when the temperature is changing more rapidly than deep in the night when the temperature might be more stable. Also, the coatings are not as resistant to more dramatic expansion cycles (remember that you need those mirrors to stay very smooth). Given the high price and low volume of the goods, it doesn't make sense to cheap out on a critical component like this and give yourself a bad reputation among a very small but dedicated community.
Well, it can federate with lemmy instances and there are way, way more lemmy users/communities than there are piefed user/communities. If you want to see the local communities on a piefed instances, it would be at
/communities/local
. This is the page for piefed.social.