You're right about the incompatibility between NTSC and PAL, but deliberate region locking was common, even in the 8-bit era. It was very much the norm rather than the exception. Also, on older consoles they simply slowed the main CPU speed down for PAL so that everything in the system matched up with the video framerate. If you've ever read about how PAL versions of 8-bit and 16-bit games run slower than the NTSC versions, that's why. And it meant that you could plug out-of-region cartridges into your console, and if you could get around the region locking, they'd often work with minimal or no visual issues, just a little slower, because the video output was hardwired for PAL in the console. I played a few Japanese games on my PAL Mega Drive and SNES back in the day, on a PAL-only TV.

The PS1 and PS2 (both very much with region locking) had a weird thing going on where any console from any region could output both NTSC and PAL, depending on what the software asked for. I believe the GameCube and Dreamcast were similar; I ran original NTSC game discs on PAL versions of all of them.

In terms of what TVs would support, you're right that it wasn't until the late 1990s that fully dual-mode PAL/NTSC TVs started to become common, but that's not the same thing as 50Hz vs 60Hz. CRT TVs were designed to work best at a certain frequency, but they were also designed to cope with variations in the signal and power supply. Most PAL CRT TVs are actually capable of synching at 60Hz, which is where "PAL-60" comes in. PAL-60 is an unofficial "standard" in which the video signal runs at the NTSC framerate and vertical resolution, but with a PAL colour subcarrier. I used PAL-60 on many TVs, some produced as far back as the early 1980s, and never found one that wouldn't sync with it. I had a very inexpensive (Under AU$15 IIRC) NTSC-to-PAL-60 "converter" for the PS1/2 that I used to play NTSC games. You mentioned VCRs; there were VCRs that specifically played NTSC video cassettes as PAL-60. They weren't common, but they existed.

I remember when Metroid Prime 2 came out (I still have my copy) and there was indeed a small controversy in the gaming press about the PAL version being 60Hz only, but it was PAL-60, not NTSC, and I played the whole game on a PAL TV that definitely did not support NTSC, without any trouble.