How is it healthy for certain awakening gurus to devalue the importance of personal relationships?
Yes, you are correct, personal relationships are important to your well-being, it depends on them.
But unbeknown to most, there is such a thing as uncondtional well-being, absolute well-being, well-being that doesn’t depend on anything, anything at all. Enlightened “gurus” and “masters” discovered that level of well-being deep, deep inside of them, and they are teaching people who are longing for that well-being how to reach it.
If you take that perspective for a second, it should make sense why personal relationships are devalued in a lot of teachings, for as long as your well-being can be given by the other, it can be taken by the other.