If you are referring to isolation as a means of attaining greater spiritual growth then I believe it is beneficial as it helps the mind gain greater control over the body and its desires. Isolation also leads to a clearer understanding of the soul. However, isolation doesnt necessarily mean finding a cave and meditating alone for six months or a year. It can also include breaking some old habits, leaving your home for a period of time and travelling to a place where you have never been before and communicating with a people or a culture which is different to your own. You would learn much from this experience, both about others and yourself. And a greater understanding of oneself leads to greater spiritual growth. This is one of the reasons people go on pilgrimage. In relation to the second question, a number of the OT prophets and Jesus, in the NT, spent time praying to God alone. Most religious prophets, whether Christian or not, underwent a period of isolation in their lives at some point, which lead to spiritual growth, a revelation, communion with God etc.
Not strong on the OT, but NT doesn't promote shunning family and friends as far as I am aware. NT says love them and if necessary forgive them for the wrongs they commit.