Sure there was. You make it look like the Rigol DS1000Z has set some kind of standard but you are forgetting that:
1) The Rigol DS1000Z isn't exactly a very good oscilloscope when looking at performance & features and it has taken years to get all the bugs fixed.
2) There are and have been other oscilloscopes from various manufacturers which also sell / sold very well into the entry level market.
3) When everyone was still working with analog oscilloscopes you could buy cheap low end analog oscilloscope as well. The only thing that changed is that technology has improved.
I believe you're joking now.
1) Include price in that equation, and you've had zero competition, literally until now.
2) None of them with the specs of the Rigol.
Price Point + Technology Level = Niche Market. Cornered from 2014 to 2018. I'm guessing they're still dominating that market for now.
3) Yes, the tech has improved. That's the point. High or low-end, most of those scopes you refer to can't keep up with the entry-level Rigol from 2014.
You can still buy cheap low-end analog scopes. That's not the point. They're not as good, and they never were! You can make biased statements about the poor quality and performance of the Rigol all day long, but you prove nothing with generalized baseless claims. Obviously the 2014 $350 scope's front-end isn't going to be as clean as a current production $12,000 scope's front-end. That's a pointless comparison. Even comparing it to a newer $500 scope's front-end, you should expect the newer, more expensive scope to be cleaner. This seems like it should be obvious.
This, by the way, coming from somebody who returned his Rigol to buy a Siglent, because I believe it to be superior. That doesn't mean the Rigol doesn't have its strengths, and that doesn't change the past 4 years of the Rigol's dominance in its niche.