How can you possibly expect ONE person to do all of this? /s

I have been discouraged to use that form because native English speakers have corrected me that unless I am a British monarch, it would be incorrect language use.

Maybe I'm missing a joke, but this is not the case unless you're using "one" as a way of referring to yourself. Saying "one could" to mean "someone could" is perfectly standard English.

One does have to be a little careful with that... It's generally old-fashioned, and can end up sounding sarcastic or passive-aggressive if the statement is obviously meant to refer to a particular person. (Cf. the upper-Midwestern "a guy could" or "a lotta guys", as in "A lotta guys would have made sure that was tied to the roof of the car before they drove off.")

If one were to use it to refer to oneself, then one might be royalty. Otherwise, one may do as one likes!