There are still UX research. It's just that the collective "we" has changed and we can/may build on some existing design decisions.

You are always designing something with a target audience in mind, and the next, e.g. mobile phone will very likely be used by someone who has interacted briefly with a similar device, so you may re-use some already learnt patterns.

The very early UXs built heavily on desktop metaphors (like folders), but at this point many (and an increasing number of) people are more familiar with OS UI n-1 than a typical office setting.

So I don't think jumping to this conclusion is correct - there are well-designed software, it has just become much much cheaper to create new ones, so the average quality has necessarily went down.