New to Discus

We're beginning to enjoy keeping some young discus. We have to travel a fairly long ways to find any fish store that will even keep them in store regularly at all (60 min drive one way). We had our local shop order in some young ones a little while back.

Here's the first one we've had for a number of months now:

Here's two others we ordered last month, just before COVID-19 shut-down:

These really young guys were bone-white when we got them, barely larger than a quarter in diameter. They've started to color up more, accepting a fairly wide variety of foods that will fit in their little mouths.

So -- being new to discus -- there seems to be a rather high-strung attitude to keeping them among some folks online. We've found no problems at all. We already keep our tanks reasonably clean, and find that the same water temperature and chemistry that suits Rams and cardinal tetras works for them wonderfully. They are active, engaging to watch, and all-round seem like great fish.

Can someone explain what we're missing? Why do they have this reputation for being extremely finicky fish?