Even ESP32, the quintessential "punches above its weight" MCU, only packs 520KB of RAM by default. At the time of its release, that was a shitton of RAM for an MCU to have!
If you ship MCUs with 16MB of RAM routinely, you're either working with graphics or are actually insane.
The MCU I'm currently working with has 12KB of RAM and it feels luxurious.
Ah, the cultural shock of going from 8 bit cores with 512 bytes to an actual modern chip.