There's sign stealing and then there's using technology to do it. The Astros had an elaborate system they used to signal batters with a banging sound when a specific pitch was coming. That's an unfair advantage that got them a World Series ring in 2017. If Houston cheated to win, the punishment should be obvious: it wasn't the best team in baseball and it needs to have its title stripped.
Saying that "Everyone does it" has no leg to stand on. Maybe everyone does, but the Astros were the team who got caught and comes with consequences. If the league wants to set a strong precedent, taking away a championship is the only option.
So the Astros have been caught stealing signs. So what? They got their punishment in the form of losing their general manager and manager, as well as a $5 million fine and a loss of their first- and second-round draft picks in 2020 and 2021. Everyone does it in MLB and just because they were caught doesn't mean they should have their World Series titles taken away.
All of those World Series teams with steroid users never had to give up their titles for something everyone was doing. Plus, knowing the pitch might help, but you still have to hit the darn thing for anything to be affected. Punishment is deserved, but something as harsh as stripping a championship shouldn't be on the table.