Of course it's not career suicide for a software engineer, and recruiters that make such claims should lose credibility with a candidate when they say these things. The recruiter counteroffer "script" ("career suicide", "you'll be fired once they can replace you", "you'll never get a promotion", "you'll be an outcast at work", etc.) is all stuff that could happen (other than the suicide part), but is highly unlikely just based on how many times we hear anecdotes about a counteroffer working out and the person staying for years.
Counteroffers are still a fairly common way to get a raise in software, although I think now that there is much less stigma to "job hopping" candidates are just as likely to move to new companies to get the raise.
> The recruiter counteroffer "script" ("career suicide", "you'll be fired once they can replace you", "you'll never get a promotion", "you'll be an outcast at work", etc.)
Sounds like you can just say, "I guess I'll go work for you then."
Back when I worked at a bank, counter offers were the standard way of getting a raise. If you had a competing offer, the Bank would almost always match that. Meanwhile, raises were maybe 1% a year. (I remember that Illinois raised state income tax at about the same time I got a raise. I had less take-home pay after both of those took effect than before. Raises didn't even keep up with the tax burden, much less the cost of living. Not that they necessarily should, but they also didn't keep up with my career growth, which is a better benchmark.)