It is not surprising that BBR comes from Van who's also designed and implemented pathchar.
I liked reading the paper when it was published and it has the merit to be simple to read
for a large audience.
I agree very much on the title as bang-bang congestion control (not only AIMD) could be
deprecated entirely by measurement based approaches like BBR.
In bang-bang cc the sending rate is obtained by a root-finding algorithm (gradient based) that
is fed by measurements of congestion (queue, loss, latency), whereas in BBR the sending rate is
an (almost?) explicit function of the measured quantities.
In theory both approaches work, but for the former we have seen a proliferation of root-finding algorithms
for wireless, large BDP networks, small BDP network, satellite, cellular, shared-media, non-shared media and more.
Selection of the right one is a question of tuning, which is extremely complex and static.
If BBR can fix that by having a unique model for all these cases that would make deprecation, as intended in the paper,
likely to happen.