There could be some truth in that for many current multiplatform titles, however we are talking about games designed to run reasonably well on the old, slow, 8-thread Jaguar processors used in the existing consoles. As far as desktop CPUs are concerned, those console APUs are comparable to AMD's 8-thread Bulldozer designs from 2011, only running at around half the clocks, and with one to two threads reserved for the OS and not directly accessible to games.
A new generation of consoles will be launching within the next few weeks though, featuring 8-core, 16-thread Zen 2 APUs. Those should be most comparable to a Ryzen 3700X from an architectural standpoint, though with somewhat lower clocks that I would expect might make their performance more like that of a 2700X. Some threads will again be reserved for OS functions, but developers will still gain access to around double the threads for next-generation titles, and each of those threads should offer over double the performance of those found in the base-model Xbox One and PS4 processors. So, games designed for those new consoles will have access to multiple times the multithreaded performance developers are utilizing today.
Most games might continue being designed with the existing consoles in mind for the next couple years, but it's highly likely that as game releases start dropping support for the currently 7-year old consoles, that they will start demanding more threads. If, as you say, developers don't bother optimizing much for PC hardware, then those games will expect having access to more threads on the PC as well. After all, do you really think developers are going to limit what they are doing on consoles just to maintain reasonable performance on older quad-core desktop processors?