Morgan from the TiDB team here. Thank you for the feedback, and I agree with you. We actually took this line out from the same copy in the docs: https://pingcap.com/docs/
(We must have missed a spot, and I will follow up and make sure it is addressed).
We try to be transparent about the differences from MySQL. On the compatibility page, there are a few cases described such as large transactions, small transactions and single threaded workloads: