Only if you need this much computing power. The typical webdev can probably get away with a quad core AMD/Intel cpu for <$200. Very few people actually need 12+ cores.
Considering I'm using docker to run databases and various services in order to do "webdev" I wouldn't underestimate how useful the extra resources are. I recently upgraded and still feel the strain in some instances.
(r5-3600, waiting for 3950x to drop, upgraded sooner because old system was acting up).
As a web dev running multiple applications at the same time with memory hogs like Chrome and Slack on a dual core work machine, having more cores do help.
It come to the point that I will have to ask my boss to replace my machine since it was so sluggish.
JS devs usually need quite a few threads/processes. The editor/IDE is 1 or more processes. Compiling is a separate, multi-threaded process. The webserver is another process. Tests are several more processes (which matters because 30+ minutes on a fast desktop isn't unheard of when running a complete test suite). Parsing the newest compile is multi-threaded in the browser. A separate core for the main website thread is especially important because opening the dev tools de-optimizes all the things resulting in significantly slower performance (a big thing with web apps). If service workers or webworkers are used, then there are even more processes involved.
Going from my dual-core Pixelbook to my Ryzen desktop is a huge change in the development experience.
It could be argued that some "developers" should be restricted to pencil and paper, but it's a different issue. Even hipsters deserve to multitask at their computer.
