Considering most big 3rd parties had moved away from handhelds by then, this was unavoidable. How many western devs bothered with major projects for the 3DS? Even the big japanese devs started petering out by the 2nd half of its lifespan, simply because the money for 3rd parties was on either consoles or mobile.
The only major exception I can think of is Atlus. Atlus' 3DS support is infinitely better than they are currently giving to the Switch.