I'm saying both the syntax and semantics (i.e. type system design) of protobuf are much superior to ASN.1 (mostly, by being much simpler and easier to understan

I'm saying both the syntax and semantics (i.e. type system design) of protobuf are much superior to ASN.1 (mostly, by being much simpler and easier to understand). I believe syntax and type system are, in fact, much more important than the encoding details. To most application developers, there is no difference whatsoever between protobuf encoding, BER, DER, PER, OER, etc., because they never see the encoding. The library and tools handle that part. As long as the data gets through end-to-end with acceptable performance, nobody cares how it is represented in the interim. Cap'n Proto's encoding is different in that by being zero-copy it actually enables new use cases, like mmap()ing a very large file for random access. Still, I'd certainly choose protobuf's syntax and encoding over ASN.1's syntax paired with Cap'n Proto's encoding.