Because you might lose 2-3 players to covid but otherwise you would've lost them to injury. Some guys had a shitload of time to recover from injuries and most people should be good. Covid is also temporary.
So with a right training camp the number of players is not an excuse.
Will the level of play be equal? I don't know. Unlikely, then again some players will know they can go all out because they don't have 82 games+playoffs in front of them, just playoffs.
What do you mean ''otherwise''? You think players who get sick magically prevents others from injuries?
This isn't a covid vs injuries situation, it's covid + injuries.
Players will get injured as well, and probably at a higher rate considering how unprepared some will be.
You're not making a whole lot of sense here, not to mention, injuries aren't contagious..
It's not about going all out, it's more about finding the chemistry and your groove back, sharpening your reflexes, etc.