I remember a long time ago when front-load washers started being a thing again, 'why don't they just make a washer/drier combo that does both?', then was so excited when someone finally did, only to find out they suck. I still look into them from time to time but they don't seem to have gotten much better. I've seen complains on the sucking at drying, and also complaints at sucking at washing, in the sense that the washer never seemed to get the clothes fully wet, in order for the drier to have an easier time.
I feel like the technology is here, someone just needs to make a good one. There's no reason a single machine can't do both adequately well.