Yes, phone tech advances fast, but. camera et lenses aren't a stationary target.
What isn't changing that fast is the need of users.
I would in fact argue that they are decreasing in terms of quality since the devices used by "photographers" are more and more screens - typically the screens of the smartphones themselves - instead of print.
The value is in the ease of sharing quickly.
The reality is IMHO two fold:
- The level of satisfaction of low end DSLRs isn't that great to start with for a variety of reasons centered around user experience and complexity of operation. Most of the owners bought them because they were hoping to get better results or for a "status" reason, but they are not willing to deal with the complexity of having to make choices, they just want nice pictures
- The level of quality of high end smart phones today satisfies the need of a majority of low end DSLR users, as well as their expectation for simplicity and something that just works. Even on my iPhone 7, it is really hard to completely mess up a picture, even in conditions when I would expect them to fail.
Cheers,
Bernard