I'd guess that a 555 is also tougher than a microcontroller. I'm putting together an HV supply and thought about using a microcontroller but opted for a 555-based oscillator. Either one won't survive HV but I think the 555 will handle stray charges better.
Modern mucus are surprisingly fault tolerant. Just saying. It’s not like the bad old days where if you sneezed at a cmos chip it would probably be fried. I’m not sure how that stacks up to a 555 though.
My mucus is about as fault tolerant as it ever has been. Sometimes it gets really thick if the weather is dry or I'm sick, but otherwise I haven't noticed any difference. I find that drinking water helps.
But even there, it's high Iq limits its applicability.