I say that their either dont understand their skills or they're just lazy.
If they dont realise that Standard step is the MAIN skill to use then they miss out on a lot. It does the most damage (until Technical Step) as an AoE and gives your dance partner a dps boost AND starts to charge your Esprit (once unlocked)



THAT BEING SAID...
People probably just look at the Standard Step skill description and not the Standard FINISH skill description so they dont understand the full power of what it does. Not everyone goes into their Action List and read skill descriptions.