Real fansub groups used to compete to be the first to release their translations, so you wouldn't have translation checks or as many editing passes.
Nowadays, the simulcasts (and the rips thereof) are faster than any speedsub could possibly be, so the remaining fansubbers definitely put more effort into quality.
> Back in the 4:3 days when anime was vbr and sources were interlaced fansub groups would go through frame by frame doing pulldown and denoising. It was amazing.
You don't need to do denoising and deinterlacing these days, so... I'm not sure why you think things were better back then? Nowadays encoders are more concerned about banding in particular, so they may specifically add noise on a scene-by-scene basis.
> When's the last time you've seen high quality karaoke on fansubs?
If you get actual fansubs these days instead of simulcast rips, you'll find they have high quality karaoke. I particularly remember the Railgun S karaoke which had realistic-looking lightning striking each syllable. And more recently, you may find the English translations have been worded so that you can sing along in time with the original song.
> You don't often see translation notes any more either.
If you're talking about TL notes in the subtitles themselves, they really went out of style. Nobody wants to be the next "Translator's note: keikaku means plan".