This is a proportionate response to an undergraduate trying to sell you his new RDBMS. But most students really did write a b-tree. Academic programming elides the supporting infrastructure that bridges the gap between algorithm and software system. Textbooks aren't generally leaving out 100 pages of extra steps required for the list to actually be sorted or the path to actually be shortest. And so a student is not exactly out of line for thinking that the Raft he was taught is actually consistent in the presence of failure. I'll defer to the community's wisdom that he's wrong! But he's still not out of line.
If anything, I'm worried about these classes instilling false confidence. People who think they know these algorithms may go implement them professionally, and not have anyone around to tell them the full story. Cryptography education is careful to put asterisks around "Textbook RSA." Distributed systems education should probably be doing the same.