WAR is a perfectly fine concept but, as with most things in life, it is peoples misuse of it that causes problems. It's a great concept BUT it's an incalculable number. Both Fangraphs and Baseball Prospectus clearly state that it's an approximation. That's not my interpretation - that's not me spinning it - it's on their websites in black and white.
https://library.fangraphs.com/misc/war/
"WAR is not meant to be a perfectly precise indicator of a player’s contribution, but rather an estimate of their value to date. Given the imperfections of some of the available data and the assumptions made to calculate other components, WAR works best as an approximation. A 6 WAR player might be worth between 5.0 and 7.0 WAR, but it is pretty safe to say they are at least an All-Star level player and potentially an MVP."
For emphasis - A 6 WAR player might be worth between 5.0 and 7.0 WAR.
There is similar language on Baseball Prospectus and any other credible organization that makes similar calculations.
The problem arises when people insist that the difference between a 2.8 and 2.5 WAR season total is absolute in its meaningfulness.
There was a suggestion that HOF should just be based solely on career WAR totals...but WAR is a calculation whose components and method of calculation have been tweaked repeatedly. Are we going to kick someone out of the Hall when when one of those tweaks drops them below some predetermined threshold? Will there be an Exit Ceremony?
WAR is perfectly fine for what it is but too many people wield it like a straw sword in their battle to demonstrate their enlightenment over those who question it. It's a meaningful and useful...very useful stat it's just not the be all and end all and too many people choose to ignore that the organizations that calculate it bluntly tell us that.