That kind of lineage as seen in Zen for instance is not a universal part of Buddhism. Actually, the whole transmission lineage concept is restricted to a few traditions and others don't use it. And in the case of Zen lineage served mainly a political purpose rather than a spiritual/religious one. Transmission is a means of marginal groups to show how special they are. The major Indian schools had no use of that kind of authorisation because they were already authentic on their own. Lineage is not a proof of realisation or even correct view. The proof of realisation is one's life, and one's mind that can hardly be scrutinised by anyone else. The proof of correct view is being able to prove it through the use of scriptures and reasoning. What kind of proof is it if a person claims authority on secret transmission? Yes, it is a level of security if people are authorised by an accepted teacher, but even that is not 100%, just check out Shunryu Suzuki and his descendants.
Im sorry, but not only do I disagree with you, I find it besmirching to the teachers and lineages of Buddhism, especially my Soto guru venerable Shogaku Suzuki.
With consideration to Jodo shu and Nichiren, every other lineage in Buddhism which exists has a lineage of qualified instructors which is in place to assure the quality of the teaching.
Every lineage (practice lineage, NOT faith based lineages) trace their way BACK to Shakyamuni, and without this lineage transmission we would not have authentic buddhadharma, and Im sorry but this is not limited to Zen. Vajrayana Buddhists are far more firm on the role of the teacher, but unless you're a yogi or ngakpa, you must have a teacher to assure you recieve authentic tranmission, lest you practice out of egotism, and lure other away from true dharma.
I cant stress this enough, EVERY indian yogi to practice Buddhism has had a guru, and this line has continued until today.
If this is not the truth, tell me the story of Tilopa, Naropa, Marpa, Milarepa, Gampopa and Maitripa. This line must exist, and when it no longer does, we will KNOW we are living in the age of decline.
That will be the day any old person can clame buddhahood without a teacher who has glimpsed the other shore giving a pointing out instruction. THAT will be the day buddhism LOSES all its relevant value in this world.