There’s no good reason today and in the future, period.
There are “experts” who still claim these, but they are based on a very dated recommendation from at least 15 - 20 years ago at this point. To some, such non-sensical requirements (by the fact that we should be storing passwords as hashes today) have become doctrine, rather than any fact based in reality.
And some users have been conditioned into thinking that these are good security practices as well, because governments and banks still make use of them, and these are the very organizations that should be the best-in-class when it comes to security. Some of these users become CEOs or product designers with more say than their IT and security experts in the company. The rest is history from there.
Oh! I forgot that IKEA has smart plugs too.
Do you have to get the Dirigera hub though? I tried looking around and there’s not much info about the TRETAKT and HA, only a few Discus threads where people suggest using zigbee2mqtt or ZHA with quirks (and it does seem like the quirk is in their repo), but no mention of whether they had the hub.