Use of Base58 in technical specifications

I'm trying to get an understanding of the use of base58 and base58check in
technical specifications (not standards), in particular, how broad the
usage is of bae58 in the non-IETF/W3C standards based blockchain
communities.

Base58 similar to Base64 but has been modified to avoid both
non-alphanumeric characters and letters which might look ambiguous when
printed. Base58 achieves 73% efficiency. Like Base64URL, it avoids conflict
with URI reserved characters, but it doesn't seem to say anything about
forbidding line-break characters (but I've never seen linebreaks in a
base58).

It has been argued: "We reject Base58 and Base58Check (for use in a URI)
due to their lack of widespread adoption."

But just because the IETF and W3C standards communities this is true, isn't
necessarily a sufficient argument that it lacks "widespread adoption".

— Christopher Allen