itch.io

what do you mean by ‘big titles have neglected over the years’?  Fixing bugs?

One often forgets the differences between indie games and big and bigger game studios. You question about testing is in my opinion not really applicable for an indie game project at the solo dev and hobby level. You do not have a publisher. A dealine. A budget and an expected return value. No profit maximization. You do not need to calculate a return value for testing efforts. Will you sell more units, if you pay for testing a week longer and delay release? Will you lose customers and reputation, if you release a buggy game? 

As an inde dev you can just release the game as soon as you are comfortable with it. Or update whatever you think needs fixing.

In the early days, it was not possible to fix games. Not easily. If your game was on the physical medium, that was it. No way to fix bugs. Especially not on video game consoles. For desktop computers, you could release fixes and patches that people would be able to get on a cd when buying a game magazine. Or over the rare and slow internet, which would cost per minute. And that came even later for console video games.

The more easily you could fix a game after release, the sloppier publishers and developers got. Now there are games, you would not want to touch at all the first year after release, sometimes longer, because of the bug festival inside the game and to see if the developer would drop the game like a hot potatoe and leave customers out in the rain with a bug ridden mess that would never be fixed. 

"Early Access" helped here a bit. But it is just shifting goal posts. When is a game worthy of "released"? As soon as you can sell it, or as soon as the developer is proud and need not be ashamed of all the bugs?