Sector, I'll remind you of a previous comment I made in a thread a few weeks back..
People do not pack a suitcase, particularly those with a kid or two or three, and drive/fly to WA and head down to the local real estate agent and ask what dwelling is available for rent or purchase. They organise there accommodation beforehand hence by the time they get there there will be sufficient accommodation for them.
In times where population growth is abnormally strong you may get a period of lagging supply as dwellings get built but as we have seen when population growth slows and houses are built and continue to be built you get a situation of adequacy or even surplus.
Everyone who has gone to WA in the past 5-6 years, and according to the ABS i think it adds up to well in excess of 400,000 people. I am confident that most if not every single one of those people who had moved to WA have accommodation. Not only have they been accommodated, the residential vacancy rate in Perth according to REIWA is now over 4%. You don't usually get an increasing vacancy and contracting residential rents because there is a shortage of housing. Median house price have also been contracting over the past three months.
