Why do we feel using variable length integers in protobuf's wire format vs strings is an instant deal breaker? Isn't understanding a protocol is going to require a more documentation than just a string field name? The kind of documentation that can often be found as comments in a protocol buffer definition file?
Having written a binary serialization format that does make the choice to use strings for field identifiers on the wire (https://litevectors.org), I can still see the appeal of using integers - they're smaller and parse faster. I've used protocol buffers in several places, including in an embedded microcontroller where parsing something like JSON would have been a lift. Aside from some issues with the impact of deeply nested buffers on the stack size, protocol buffers worked brilliantly, and allowed us to keep a consistent data representation across multiple languages and platforms.
(biscuit author here) I tried a lot of different formats, especially looking for something that generated small tokens, that could have a canonical form, and that was supported in a lot of languages. The canonical part was a dead end as most formats did not support that well. Protobuf ended up being the one which generated the smallest tokens, and was easily supported in most languages, even if, like you, I don't agree with everything in the way it's serialized.
Self describing formats were a dead end as well because it grows the token size
