Adding to Ismelda’s comment: you can already do that by using the Other video library type and the personal media agent.
Plex needs the structure to match your media – if you can live without the matching / automatic metadata… or if you’re ok with your own embedded metadata, use the other video type.
Other than that there’s already a number of existing suggestions asking for more flexibility in particular with tv-show content – down to specifying your own regular expressions in order to determine the different information required to match your content.
While those requests pop up occasionally, none of them has gained much attention/support.
