Because people are too cheap (or fail that hard at basic analog electronic control) to get a proper single-pole single-throw switch with a pair of MOSFETs in a monostable mode, or use an S-R flip-flop latch to debounce, or even a very simple R-C filter circuit.
"Throw a microcontroller on it and call it a day" is the surest sign of someone not properly educated in electronic engineering.
If you live under a waterfall you'll use 1000 gallons of fresh water pumped at blasting high speed to wash a cup.
We live under a waterfall of cpus and gates in general, and organisms don't care if their environment is perverse. A thoughtless organism will happily consume 1000 units of a free resource just to get 1 unit of some other non-free resource.
And a lot of humans are the worst. Thinking beings who elect not to care about anything like that. Like spammers that operate simply because sending email is free for the sender. They get almost nothing from it, and it costs everyone else a lot, but it costs them even less than the tiny bit they gain, and the external costs don't matter to them the tiniest bit.
But the environment is perverse, created by economies of scale and Asian slave labor and the push for advancement for it's own sake which makes existing useful things artificially low value by being "obsolete".
A software version of that might be making apps with Electron. It doesn't matter how much cpu and ram and disk and general mass of tech stack it takes to make some trivial app. The developers precious time outweighs all other considerations. If they can make the app in a few minutes with no effort instead of a few hours, it doesn't matter how much of everyone else's resources they consume since their time is valuable and 1M other people's cpus are free.
