That’s incorrect. UFA was 31 pre-2005. It dropped from 31 to 27 as part of the post 2005 lockout CBA.
en.m.wikipedia.org
There isn’t any real comparison to be drawn to the 1990s because now there is (1) a salary cap, (2) an individual player cap, (3) revenue sharing, and (4) a limit that 57% of revenue goes toward player salaries through the escrow system.
NY can’t spend 3-4x as much as another team like they did in the 90s, or pay McDavid the equivalent of $20 million per year like they could have done in the 90s. And because of revenue sharing the Canadian teams aren’t going generally going to face the same financial issues they did in the 90s, especially since the league won’t be spending 75% of revenue on salaries (as the league claimed at the time) like they were back then.
I think on balance a significant further reduction in the UFA age would benefit the premier destinations in the league who would have more opportunities to buy players, but to a limited extent because they would always be limited by the cap and the need to sign other players to fill out their roster and we’ve seen that players rarely take big discounts. But if anything I think the primary disparity it would create is magnifying the tax advantage benefit teams in low tax jurisdictions have.