I don't think damage is an issue, within reason anyway.
But if you only block one tire, you have to go twice as high with that one tire to get as much lift as you would get putting the same number of blocks divided between two tires. So for example, why put 4 blocks under one tire instead of two blocks each under two tires. Makes no sense to me.
That's oversimplfying to make the point, because at some point the unblocked axle would be hanging. Other than wanting to change that tire, what would be the reason behind that?