Doesn't that mean you just have to reserve a different pin for the bootloader, making it moot?
Nope, just add jumpers. That way you can disconnect the jumpers when programming, and reconnect them when done. I've used an Attiny85 this way before, it works quite well.
Also, if the pins chosen are ones used as outputs then depending on the applications you can probably get rid of the jumpers.
But if you think about it, if you need a HVP, then you would need to be able to isolate all 5 pins in order to program it. For a bootloader you only have to be able to isolate 2.
If you are using a DIP package it doesn't matter as you can simply pull the chip, program it, and then plug it back in.