In this case it does.
This shows how you need to know limits of your instrument.
They used signal that spans from +2V to -0,4V.
Then they offset it and go to 20 mV/div.
Top of the signal then overdrives input range of RTB2000 that has quite bad recovery from overdrive (it has been shown, RTM3000 also has recovery artefacts) and it distorts bottom of the signal it is showing. At 100 mV/div signal is still perfect. But at the 20 mV/div it distorts badly.
MSO5000 seems to have either better dynamic range (so it doesn't distort yet at same settings) or much better overdrive recovery (they seem to claim that they have very good recovery compared to other scopes) so even on 10 mV/div it doesn't distort. At that level it still shows full res, until you get to 5 mV/dir it is not digitally zooming anything.
So for this particular case, and by using both scopes the same way Rigol wins.
Fact is that because of 10bit converters, you could actually use RTB2000 at 100 mV/div and than use zoom (digital zoom with finger) to see same signal without distortion. So you could see same thing by using scopes differently,each to it's own strength.
This also show how "cheap" manufacturers can make things that are in fact better at some corner cases, and also that because it is expensive RTB2000 it doesn't mean that is superior in every case.
Also it shows how most people misuse DC offset function. It's purpose is to offset constant DC offset form a complex signal so, for instance, you could look at milivolt level noise on top of of DC power bus or something. It is not vertical position button as we are using it most of the time. Also, because of limited dynamic range, you can't actually look at mV level noise on top of 5V bus because you don't have so much offset range usually. For that you'll have to AC couple the chanel. So offset is not so useful as you would think.