I usually see full-stack and DevOps roles as being a creation of the startup and early growth phases of a company. In those phases, the market and product definition is changing rapidly. Whatever you lose in reduced technical depth of these engineers, you gain in reduced communication costs, faster ability to make changes, and additional context and ability to spot efficiencies because they understand the full stack. And these companies are usually default-dead anyway, so if they screw things up and cause an outage, it's no worse than if they build the wrong product and have no users.

I've never seen a DevOps role in Big Tech (I've ping-ponged back and forth between the startup and FANG worlds a few times), and usually a full-stack engineer is someone very senior who designed a lot of the product when it was young and stuck with it for a decade. Instead there's usually a clear SRE/SWE split, and hyper-specialization, enough that someone might actually become the expert on one particular screen of a mobile app.

If you're frustrated with the de-specialization of roles, it's entirely possible you're working at companies at the wrong stage of their lifecycle. Move to a big company and the struggle is to avoid becoming pigeon-holed into one very specific task (and then laid off when the structure of the product changes so that task is no longer necessary). Such a career change can be challenging at first because your career can get specialized to "working for startups and early growth companies", and then big companies won't even look at your resume. But if you try enough places and say in the interview that you're looking for a place where you can really specialize and develop expertise, you can often find a manager desperate enough to take a chance.

LLMs are another issue. I'm worried that they're going to make the economy very unstable because the whole reason a firm exists is to capture institutional knowledge and the LLM captures that institutional knowledge in the model, where a.) it's not specific to a differentiated business and b.) it's subject to model-collapse issues. Could easily see the whole technological world collapse through lack of expertise, but if that happens it's a bigger problem that you can only fix by developing the expertise yourself.