From what I understand, in China during the Golden Age of the Tang dynasty, the various Buddhist schools (Chan, Tien-Tai, Hwa-Yen, Pure Land, Vinaya, etc) had not yet become sectarian and it was common for monks (and serious lay-people) to spend extended time in various temples and schools.
And in the Zen (Seon) tradition in Korea of today, monastics too would sometimes wonder and visit teachers other than their principle Dharma teacher. Probably after getting some solid grounding with him or her, first.
So, it is not an exclusive guru-disciple relationship. Nor is it with Tibetan Buddhists, I believe. They too often have more than one teacher. But there does seem to be a lot more formal ties and vows cementing the relationship than in Zen, which may be as deep, but a lot more informal.
As for being hierarchical, I guess this is more of a cultural/style thing than a Mahayana thing. Some teachers are very informal, others draw a clear line. Both have their pros and cons. And then there is a point when a student becomes an equal or even a master to his former teacher. There are many records of that in Zen lore and it is based purely on the level of insight. So it is not a fixed relationship by any means.
As for the point about meditation and Right View in general, I think a teacher can be extremely helpful and save an enormous amount of time (lifetimes?). I recall my first retreat when a whole bunch of clever nonsense was knocked out of me.
Always more where that came from unfortunately!