[evanj]

You make an excellent point: probability says a 4-byte CRC32C provides much weaker guarantees as the length of the message gets longer. These CRCs are typically optimized for pretty short messages, and that is what I had in mind when I wrote that article (e.g. the kind of messages that might get exchanged as part of an online serving system).

For overkill discussions about these issues, see

"32-Bit Cyclic Redundancy Codes for Internet Applications" which talks about the kinds of errors that various CRCs are guaranteed to detect: https://users.ece.cmu.edu/~koopman/networks/dsn02/dsn02_koop...