You don't need a resume if you stay at the same employer for 40+ years. Win-win!
I you're happy there, why not. Unfortunately over the last few years I got the impression that loyal employees don't necessasirly see the appreciation they deserve by their employers.
Getting a raise often becomes increasingly hard once you're working there for long enough. Switching jobs or even companies is often the best option to get a raise or better benefits.
There's plenty of big pond companies with enough roles to keep someone learning and improving for decades.
That said, unless I completely change my role and/or specialization, I don't see any room to grow.
I'm a frontend engineer with some fullstack mixed in. Going backend would certainly be an interesting change, but it would be at the cost of atrophying frontend skill/knowledge, the end result being it would be harder to get a future FE (atrophy) or BE (beginner/mediocre skillset) job. Especially since companies these days seem to be creating FE specific interview tracks.
That would be the point, yes.
I definitely did not mean to imply that spending 6 years doing the same thing at a big company is in any way better than doing the same at a small company.
My point was that since a large company likely does allow you to completely change your role, domain and specialization without quitting, you should look at years-per-role and not years-per-company.
They prefer to bring in/hire more candidates from other countries and pay them less than what current employees ask for them, because it is cheaper.