To a certain degree that is true, but they're also much more replaceable.

Not only have I seen multiple organizations lay off entire frontend groups, but as time goes on I work with more and more people who specialize in only this end of the stack and need people like me to wade in and solve actual problems for them.

Under the hood I know how things actually work and I can quickly get up to speed on their issues, whereas it's not always so easy going the other way.

Also if I had a dollar for every time I had to help web engineers "figure out" why the Sentry p95s are so high when sending large binary blobs on multiple round trips between Eastern US and Japan, I'd be a rich man.