1st of all, I didn't write either of those articles. They were written by previous mbu keepers, the 1st author has 50 years of pufferkeeping experience behind him. This was his wish for his next mbu:
"Unless you have the space, the time, and the price of luxury car to put into a fish, they are just not suited to private keeping. If I could and was willing to do it over, I'd devote the entire tank room to the one fish. It would house only the single tank, Monaco style, custom built in place, with customed filters and automated changes."
"They are just too big. His system was the 180 with him, a 120 veggie filter, two 40-gallon veggie filters, a 20-gallon Daphnia filter, a 20-long filter-feeding shrimp filter after the daphnia tank, plus a twin-tower W/D, two large Eheim external canisters and multiple internal Eheims, and 2- or 3- 50 gallon partials per week (alternating weeks). "
All this filtration & the 1,000g tank size is to dilute the huge amount of waste this fish produces, not necessarily just to give the fish swimming room.