No practice requires a teacher's guidance to practice. Shakyamuni Buddha himself said, be a light
Really, the whole structure of Tibetan Buddhism is Indian Tantric Buddhism grafted onto warlike power cults of the Tibetan plateau. The rituals of Tibetan Buddhism are taken from Bon, which is a shamanistic and animistic folk religion of the area, one that is seriously tribal and based upon a lineage-centric power cult. In Tibetan Buddhism, a student is told that they CANNOT attain enlightenment, and cannot even practice the religion unless they receive a series of "empowerments" from the guru, empowerments that all cost money. The guru (or teacher) is the ultimate authority source. Nothing the guru does or says can be questioned. They are always right, and you must always do exactly as they say, so that they can pass on their Wisdom to you. Needless to say, this has ld in the West to numerous sexual and financial scandals.
Nothing in Tibetan Buddhism is done for free. There is always a price tag attached.
I received one empowerment during my involvement with Tibetan Buddhism. I stood in a long line of people who were taking gifts to the guru for giving them this empowerment. Everybody else was just pouring money into his hands, at which he would nod and smile at them. I had some beautiful polished stones that I had carried around in my pocket for years, and which were special to me and quite beautiful. I placed them in his hands, and he did a double take, and then frowned and glared at me. I was ushered away by his supplicants in their robes. The money train then continued, and he resume smiling.
The Dalai Lama claims to be a poor monk, but if you look at pictures of him, he is always seen wearing a Rolex, a particularly jeweled Rolex.
Pick up ANY book from Snow Lion books or Wisdom books on Tibetan Buddhism. Somewhere in the first few chapters, you will ALWAYS find a statement that these teachings (for which you have paid a hefty price when purchasing a book) cannot be followed or understood "without the guidance of a qualified teacher or meditation master". You've already paid for the book, and then you are told that it is useless without submitting yourself to a "qualified master". Which means of course, get out your checkbooks or your plastic (though they prefer it in cash.
Nothing in Tibetan Buddhism is done for free.
The Zen Centers I frequent may be doctrinaire and bureaucratic, but the teachings are free, and you are never told you cannot attain enlightenment without a master. To reiterate: Shakyamuni Buddha himself said, be a light
unto yourself. There is talk of mind-to-mind transmission between Roshis and students, but that is only if you wish to BECOME a teacher and join the stream of their monastic culture. One can practice alone and without guidance and get to the place where Shakyamuni got.
In Tibetan Buddhism that door is closed to you unless you invest money and devotion to a teacher whose every action and desire cannot be questioned. It all come from warrior power cults in Central Tibet, that grafted basic Buddhist teaching onto them, and added Bon animism and shamanism to make it look colorful and attractive to their gullible audiences.