The 186 is a Permanent Residence visa, the 408 is a temporary (up to 3 months, 2 years or 4 years for government - normally not extendable over 4 years).
That poster working in "film production" (don't know what sector of that field) was self employed in UK and intending on living in Australia permanently.
The restrictions on visas like the 408 including no pathway to a Permanent Visa make it hard to find good candidates when a position/s need to be filled by overseas person/s. If you could only work for 2 years then move to another country and find employment again - would you pick Australia or a country that pays higher expat wages with renewable contract option?
There could be another GFC in 2 years time.