On-line covens are really much more to do with "socialising" than actual learning. Yes, there are "gems", but also a lot of dross! Nothing beats contact with a real,live coven; or better still a personal teacher.
I was extremely lucky to meet, and become a life-long friend, with a real witch.In an on-line coven one is still only "reading" about the Craft; just as from books!
But I was "shown" the magic! As a small boy I watched the crystals grow. I saw the magic of photography.(And anybody who thinks photography is not magic; don't understand magic at all!)
I was shown all the magic of Nature; as well as reading about it!
I was shown the real meaning of life and death, and the Circle of Life.
That is knowledge that simply cannot be taught merely by reading about it, as in an on-line coven!
However, an on-line coven has its uses as "the next best thing"; so long as one is mature enough to separate the Chaff from the Wheat!