They were state of the art in freshwater back when I started. Guess folks still use them today. Getting old has only one advantage, perspective. We have come a long way in a few decades.
Protein skimmers and the Berlin method using live rock
Good heaters and chillers
Circulation augmenters, like fans and pumps
Filtration media, we had charcoal and filter floss, period.
Accurate test kits, we had ph strips.
and a host of other things.