They only recommend that because some digital pedals leak noise into the power line that gets picked up by other pedals.
Some, but not all. EHX, Digitech and Zoom are notorious for it, but Mooer and TC have pretty good filtering in my experience and are fine sharing power. Like I said, experimentation is the way!
You don't get it of jail free by putting two of these noisy digital pedals on the same splitter either. Especially as many now like TC and Strymon have an analog dry through signal path.
It's not just digital ones you want to watch out for, any pedals that double to 18V internally might need isolating too, as I found to my dismay with the RMI Basswitch compressor.