Whilst true it's not really related to the suggestion.
The problem is that currently only the FSS explicitly shows whether a planet has POI. Say you scan a system and afterwards you want to check out planets with POI.
Except in the system map (where you'd expect such information) there is no way to tell which planets have POI and which don't. And yes, if a planet has active vulcanism chances are it has geological POI, but again this is not explicit and no solution for biological or alien ones.
So in order to visit, say a biological POI, you're forced to return to the FSS and select the planets one at a time, even if you've already scanned the system.
Hence the suggestion in the OP.
What makes this even more frustrating is that it forces you to wait until the "scan" is finished for each planet if you're hunting for specific POI. This sometimes, for whatever reason, can take up to 20 seconds. This adds up quickly for big systems. It's all just a big waste of time and extremely cumbersome.