FWIW, it seems early SOA placed a lot of emphasis on the bus and the middleware[1], with the problem being solved having more to do with enterprise governance[2], not one of software architecture. It seems to me, true scotsman and all, that modern micro services architecture has emerged from a first-order attempt to solve actual problems around both scaling vertically and collaborating on large systems in large organisations.

1: https://en.wikipedia.org/wiki/JBoss_Enterprise_SOA_Platform

2: "OMG how do we keep track of all the stuff running on all the servers? Multiple versions, multiple languages, multiple OSs? This sounds really scary, no, leaving it to the nerds is not an option, think of the BUS COUNT!" (caricature).