The phase check is not really necessary if you have properly connected the speaker cables.
Also, you can actually verify with your ears whether your speakers are connected in phase. With the proper phasing, you hear a fuller sound with increased bass.
It's actually important for me since I couldn't easily hear phase differences after calibrating with YPAO and Audyssey, but when doing checks after Dirac Live, the difference of in and outta phase was crystal clear. Probably because it adjusts phase based on their impulse calculations.
I bring it up because both Audyssey and YPAO complained about the phase of my Polk R700s, but everything's connected correctly.
I agree that those YouTubers are charging a lot for their calibration files. It's not a good look.
I did buy the new HD Spears&Munsil disc as well.
I thought Spears&Munsil cost a lot more honestly. After finding out the price, I wondered why the YouTuber one cost so much.