I wouldn't say it is not valid, more like "less ideal". Because an in-person coaching can see your entire body whereas an online coach can only see as much as the camera shows them. Unless you have a cameraman moving along with you, it is quite challenging for the coach to pinpoint the issues. Another usual issue is the connectivity, lag and (uncommon but important) real sound. What do I mean by real? Well, my trainers (the first one taught me how to skate, the other - current one, is teaching me figure skating) can literally hear if I am not using the correct part of my blade. I was practicing my jumps and my coach said to do it again because he can hear me landing on the wrong part of the blade and that could be bad for my knees. Minor things like using the wrong part of the blade when stroking, or landing on the wrong part of the blade etc can lead to you developing bad and harmful technique.
If you don't mind sharing which country you are in, maybe we can help with the options. For example, I live in Moscow (Russia) and we do have coaches that offer online lessons along with in-person coaching. But, depending on where you are, you may find it difficult to arrange time (timezones) and payment (no visa or mastercard here for obvious reasons) for the lessons.