Hakko 936 chinese knockoff power supplies

[sh590]

Hello,
I've been looking for a cheap 936 soldering station on Ebay and I've noticed some of the soldering stations operate in 110V and 220V.

For example - https://www.ebay.com/itm/936-Power-Electric-Soldering-Station-SMD-Rework-Welding-Iron-110V-220V/401205182210?epid=2115429791&hash=item5d69b13f02:g:~B0AAOSwYIxX~Kjz

As I understand, this means that the PSU inside is switched-mode power supply as opposed to the PSU inside the original Hakko 936.
This raises a lot of questions to me 

Why the original Hakko didn't use switched-mode? It's smaller and lighter isn't it?
Does this mean the Chinese soldering iron uses DC instead of the 24VAC?

And most importantly - Is there a reason to prefer a lenear PSU even if it costs more?