It really depends if you need the absolute time and height of two pulses to continue my example. Consider if an energetic particle hits a detector where the pulse height/area is a function of the energy deposited and I need to know the arrival time of the two pulses (as well as the areas). I can't really do that with a frequency counter because the height might be small (and dispersion might change the area/shape relative to the height) for one energy and large for another. If the accuracy of the time base is 1 ppm, then I know the time scale on the bottom to a fractional accuracy of 1/1000000. In the case of this scope given the sample length is only 200 Mpts, and the sample rate is 2 GSPS, then we have 1/10th of a second maximum capture length.
This means the time precision is about 1000 times better than the accuracy. If you captured a correlation between two pulses with two of these scopes exactly at the limit of their memory then the error in time could be as large as 200 ns between the two scopes in the 1/10 of a second. That's a shift of of about 400 samples between the two units if they are at the opposite extrema of their spec. If however their clocks were calibrated to 20 ppb, then it would only be 8 samples.
In truth the absolutely accuracy is less important in most cases than the stability. If you look at this decay process that's generating these particles again and again, the arrival times can be averaged though still not captured by a simple timer/counter unless you build a custom discriminator for the experiment. This is why the short term stability is important. It really just depends what you are doing with the scope. I do scientific measurements all day, both at home and at work. These tools aren't generally designed for us as we have weird corner cases but generally link all my instrument's 10 MHz inputs to a master when doing time correlated measurements and care about absolute time accuracy.
Anyway you cannot expect all instruments to be class leading, I get that, but it is possible to get better time bases than what is in most scopes for not very much money.