Why is a dehumidifier either a hack or a lie?

smartvacuums.co.uk says a dehumidifier collects 10 - 20 litres of water a day. dehumidifier-rentals.co.uk says 8 - 20 litres a day for a domestic compressor type, or 0.5 - 10 litres per day for a small domestic type. upgradedhome.com says about 4 litres a day.

Sounds plausible for a mop water bucket to fill usefully full between, say, twice-weekly moppings.

every time i post an amazon link people downvote me but i'll do it for you. this is not a referral link, just copied straight from my order history https://www.amazon.com/dp/B0DGXRQQ3H "3i S10 Ultra Robot Vacuum and Mop with WaterRecycle System"

it would be pretty impressive if its a marketing lie, as i've had the robot running for about a year and haven't had to refill the water tank. it's "just" a dehumidifier. i live in miami so plenty of moisture to go around.