You must not know a lot about Old Believers to think that they are more likely the real Russian Orthodox Church. How do you see them as having a better claim?
They preserve Tradition exactly as it was handed down to them. They do not seem willing to compromise with modernity. They are truly “not of this world”.
Not all raskolnik sects lack priests or bishops, but in answer to your question - yes, or rather, it doesn’t seem to decide either way. Traditionalist Catholicism has a better claim in my mind than the hippie Novus Ordo version to be real Catholicism, and yet traditionalist priests are few and far between.
Or the lifting of a minor custom to the level of infallible doctrine?
As the Greeks did objecting to the Latin use of unleavened bread, celibate priesthood, and the separate development of the Tridentine liturgy (or what would become - with very minor modifications - the Tridentine liturgy)? Without a Magisterium headed by the Pope and guided by the Holy Spirit, you don’t have an objective criterion for where to draw the line. Who has the right to change anything? By
whose right can you change anything? By your own? By an ecumenical council (even though none has taken place for over half a millennium)? Modifications in the practice of the Faith can only be undergone in the name of the Vicar of Christ - whom Orthodoxy rejected.
I do not reject their right to practice as their ancestors did, but their complaints against following the older Greek tradition concerning how to cross one’s self is on the level of absurdity.
I agree- which is why I am Catholic, thereby avoiding the whole problem of the lack of an authority with the Keys of Peter which plagues Orthodoxy.
What makes them canonical is their communion with their primate, and upholding of Orthodox teaching, doctrine, and theology. Occasionally, minor schism is permitted within Orthodoxy (I.E, a schism lasting a few years such as the Bulgarians in the 1800s, and the Russian Orthodox outside of Russia in the 1900s) but after a few years they get back together with their primate see.
Then Orthodoxy lost its canonicity when they broke with the See of Peter, since the primacy of Peter is something we all agree on, both Catholic and Orthodox.
The Russian Orthodox Church existed before they broke communion with the Roman Church, just as the Great Church of Constantinople existed before the schism.
As a particular or local Church, yes. As a national denomination with its own existence separate from the whole (Catholic) Church, it came into existence when it separated from communion with Rome.