Let me try a different perspective on this.
In Tantra, one must see one's Guru as a Buddha. In Tantra, this is done as an internal or subjective practice. It is not to be done on external or objective basis. (In Gurupancasikha - 50 Verses on the Guru - it is even explicitly forbidden to prostrate to one's Guru on certain occasions due to this.)
So, whatever one might think about someone being a Buddha, it is to be done in secret. After all, Tantra is called the Vehicle of Secret Mantra.
If one practises like this, internally, in secret, there will not arise problems.
But the moment one takes that view into public, into the open, one will get lots of problems. For after all, my Guru is not your Guru, and therefore he who is a Buddha for me, is not a Buddha for you, and vice versa. And if the whole population happens to be Vajrayanists, as in Tibet, one will therefore have a nationful of conflicting "Buddha-claims" in the open.
And once the identity of someone with a certain Buddha becomes institutionalized, as it happened in Tibet, the problems just escalate. For if the institutional head of some organization is "given as" a Buddha, in a public social sphere, then even those who have no spiritual connection to the said person, are forced to accept him as if he would objectively be a Buddha, or else be automatically and by default be labeled as "political opponents" to the said 'Buddha'.
To rephrase: If the internal practices of Tantra are 'outed' into the public and political sphere, one is doing something else than Tantra; one is making a claim of supreme authority, that is, one is practicing mere power-politics.
If the institutional heads of TB would all just be like Ganden Tripa, a person elected to be the head of an institution, a heir to the seat of the founder, there would not be problems. All organizations need some sort of Head Person, and it should be left just as is. A monastery has an abbot, and a school has a head. But once someone is presented as a Buddha, in the public sphere, the Tantra gets flinged away and the Politics step in.
I feel that the Tibetans pretty much destroyed Vajrayana by taking internal personal practices and twisting them into external public policy.