Yeah, of course it was the worst - and it was what developers where expecting how it's in most homes, RF or Composite at best. And it's how they developed those games, with multiple CRTs, to see how their art behaves in real world, versus monitors they were designing their games on.

As I said, I went into home video gaming around '83, and all my friends and me had those systems (ZX or C64, it was more or less even split) hooked via RF, or composite at best...so that's how I remember them.

In the late 80s I was on Amiga 500 hooked to TV first with composite via modulator for a short time, then via SCART.

I don't know about that. A lot of tvs in the late 80's had really good comb filters. Edit: Nope. I can't actually verify this. It may still be true, but until I can get my hands on a good 80's Trinitron for testing I can't make this claim. Composite going to a TV with a good comb filter looks like S-Video. Sure, only 10% of households had them but a lot of companies wanted to support the cutting edge of tech. Also a lot of games were ported from the arcades or computers where inputs were more advanced. There was even an arcade version of Super Mario Bros. The PPU chip in those cabinets was used to make the first RGB mod for NES. 

Edit: My friend has an NES on a brand new PCB with all new caps. The composite output on it is godly and would have been what a new NES in 87 would have looked like. I'll post a pic later today. 

If I remember, I will look when I'm at home later.  I remember it's a 10" screen, and it isn't a BVM.

Mate, you will just have to believe me on this one (or someone else around my age, who was their in early 80s and played video games at home) - RF or composite at best, on those late 70s/early 80s CRT sets looks quite different than on PVM/BVMs that part of retro community has fetish with. Are PVM/BVMs better tech? Absolutely. Is that what we were playing 8-bit video games on? Not even close.

It wasn't until I got into retro gaming, that I really understood how much that connection wire really matters.  The first time I played on an HDTV, I thought it was a huge graphical upgrade, but I had only been using composite or RF before then.  That HDMI cable was actually where most of the upgrade came from.  Once I started using RGB or component cables on older consoles I realized just how much I'd been cheating myself all of those years with a composite connection.  I played FFX with a PS2 on my PVM, and it looks amazing.  Those high resolution cutscenes that you occasionally get in the game look as good as anything I've seen on a PS3 or PS4.

Back in the late 80's and 90's, computer monitors looked so much better than console games.  But yeah, every C64 I ever saw was hooked up to a normal TV and we were all using RF connection back then.