I have also never heard that it would break one to do so.

The people making this claim all say they work in repairs. I don't think any of them are saying that one (normal) foot-flush is enough to do it, just that the mechanism can only take so much cumulative force, so if (using fake numbers) it could withstand 10,000 normal hand flushes it can only take 7,700 foot flushes. Or whatever, I don't know what numbers we're working with.