One thing that is noticeably different these days versus "back in the day" is the nutrient levels. Back then, Nitrates and Phosphates were taboo so emphasis was indiscriminate removal. Big skimmers, GFO, Nitrate reactors. Basically everything you could do to strip everything down. I think modern reefing is much more comfortable with higher nutrient levels.
On the flip side, lighting was a little less scientific but a tad easier to use. Metal Halide, T5's, etc. afforded a margin of error as far as coverage. Obviously, our electric bills paid for that ease.
Not sure how "old school" it is but here's what my equipment looks like in 2010.