Calling PETG "utterly problem free" is quite a stretch lol. PLA is pretty objectively much easier to print than PETG, and perhaps than all the popular filament types out there, especially if you are trying to print anything where precision/detail matters. .
PETG is just oozier and stickier by default, so stringiness is almost guaranteed to happen, bridging at a greater risk of failure, etc. It is tougher, so unless you have a printer that can use multiple filaments on the same print, removing supports is more difficult.
Can you reduce these factors by tuning your 3D printer - yes, a bit. But that's not "utterly problem free".
PLA is the plug and play of the 3D printing world right now.
When you print objects with 10's of printers 'tuning your 3D printer' is no longer an option other than to tune it to be 'in spec' You can only tune your designs and the profile for your filament and for a particular model of printer but then all of those have to be close to identical. As soon as you start tweaking your design or filament profile to offset possible issues with the printer you've lost reproducibility.
Incidentally, a lot of the stuff on thingiverse and other similar sites suffers from those kind of issues. They are tuned for PLA on a particular printer without realizing it.
PETG is just oozier and stickier by default, so stringiness is almost guaranteed to happen, bridging at a greater risk of failure, etc. It is tougher, so unless you have a printer that can use multiple filaments on the same print, removing supports is more difficult.
Can you reduce these factors by tuning your 3D printer - yes, a bit. But that's not "utterly problem free".
PLA is the plug and play of the 3D printing world right now.