I too, understand your point on how the term "full stack developer" is being abused by some companies. In a former job, I was the only web developer, and I did mostly back end but also had to do simple front end (and database and server management on different environments). I remember telling my boss at that time: "You know that you're getting a bargain with me with what you're paying me right now, cause if you paid me for all the stuff that I do here, it would almost be double of my salary".
But I understand what you're trying to say, is that a lot of companies use the term to justify a mediocre salary, when you could be gaining more of all the efforts and knowledge that you're giving to the company. I'm kind of that situation right now. I've done many different things here where I work right now, and feel underpaid. Yes I love doing my job, but I also feel being ripped off.
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