pg_receivexlog only captures WAL data, not *.backup?

This is on 9.6 and I have not tested on 10 yet.

The docs mention being able to use pg_receivexlog in stead of
archive_command as main backup method, I wonder how this is possible?

I did observe that no such *.backup file gets copied by pg_receivexlog
after the server was put in and taken out of backup mode.

It was my impression that *.backup files were required during PITR to
mark the point of consistency.

Is this not or no longer the case?

Or, I wonder if it depends on pg_basebackup being used w/one of the
options that captures all WAL as part of it?

Also, I did not (yet) test to see whether timeline *.history files get
copied if pg_receivexlog was pointed at a standby that was then
promoted.

Thanks for any insight.
--
Jerry Sievers
Postgres DBA/Development Consulting
e: postgres(dot)consulting(at)comcast(dot)net
p: 312.241.7800