> They address a specific category of low-cost, high volume, non-serviceable products with limited functionality. You need to wait for the push of a button and then let an LED flash exactly five times? You need to control a battery-operated night light? The sub $0.10 MCU is your friend to reduce BOM and shorten development time.
These are cheaper than 555s, more easily available in various footprints, need almost no supporting passive circuity or glue logic, lower power usage, and more flexible to boot.
Popularity of the 555 waned a long, long time ago.
More accurate timers, too. It's bizarre to think that "program a microcontroller" is actually cheaper - even in small quantity - than the 555 designs I remember building as a kid.
(In single quantities from LCSC the cheapest 555 is $0.07 and the cheapest Paduak microcontroller is $0.04 - in quantity the 555 is $0.04 and the Paduak is $0.025. Plus fewer support passives with the Paduak.)
For the push button example I can envision using a pair of 555s or a 556 as a timer for the flashing and a latch to store the success condition, but how does it count to 5? You need more logic in here, so why not a cheap programmable chip?
If you're allergic to 555s, I guess?