They have also cancelled Ballina according to that article. Qantas recently announced a daily Syd-Ballina Q300 service.
Rex has never tried to be competition to QF, they know they can't win that fight. They go after smaller regional routes QF has long given up on. If anything, Rex should be thanked for building up routes to be strong enough to support QF service!
The only route that I can think of where Rex went up against QantasLink when they were already established is Armidale. ARM was a legacy Kendall route but QantasLink pushed Rex out of the market at some point in the 2000s (not sure when?) but ZL subsequently resumed ARM in 2015 against 4x daily QF. Both have seemed to coexist there relatively well, and of course they also both serve WGA and ABX.
Blaming BNK on Qantas seems like a stretch. I'd guess that route was already very tenuous as both VA and JQ can serve the route at much lower costs, and ZL could only hold on by serving the business community with an early morning down and evening return. As soon as QF announced a comparable schedule they didn't even bother to compete and left straight away.
They have both been on SYD-DBO for years too.