On paper a well-funded 401k is better. You don't have to worry about the fund collapsing. You're safer against inflation. And your money doesn't disappear when you die. Etc.
12% matching is an insanely good deal for people smart enough to use it well. But you are going to have people who make really bad choices end up in a lurch. So it's a higher-ceiling/lower-floor range of outcomes for each individual.
if you are 50+, worked there 30 years, and had your pension frozen after 20 years of work, you are so far behind the curve even if you max out your 401k for your remaining years. You need to do a lot of work and probably invest in high risk stocks to even begin to make up for that 25 years of lost compound interest in your career.
Also: I realize I'm spoiled, but I had quarter matching 401ks in tech (which apparently isn't that amazing to begin with), so I don't see this as an insane deal for the effort and sacrifice they put out.
Even if you contribute late, you probably don't need to draw down on the 401k until much later in your retirement to make up the difference between your pension payouts and inflation. So that could still mean a few decades of compounding growth.