Fan complacence, drawn out gradually in a sea change stretching pretty much an entire century. For most of the gloved era there's been not just one single world champion, if we're being honest. You had NYSAC and NBA saying their guy was the man, and people of the day nodded along to both, saying "yeah alright that's reasonable". Whether due to whom the belts were held by in either instance ("champ makes the belt"), or just the fact that people are on the whole fairly pliable and will listen to any institution claiming to be telling us what is what, I couldn't tell you. Probably admixture. Then, suddenly the IBF splinters off and people are like "well, there are two. I guess three's reasonable." Patience began to get taxed with the advent of the WBO, and for most of the 1990's very few people outside the UK and some parts of continental Europe considered them on par with the Big 3. It took almost two decades of their pluck and persistence and striking gold with the odd highly-respected titlist (ie Calzaghe, Michalzewski etc.) among some mediocre dreck who likely should've topped out as Euro champs (ie Gert Bo Jacobsen, Magne Havnå etc.) for everyone to shrug and reluctantly accept them crowding into a now "Big 4". A fifth would be more than pushing it, as we have seen with the IBO's uphill climb attempting to match footsteps on the WBO's trail. Nobody wants a 5th; most think four is too many - now, in hindsight, but few of those silent majority argued too vociferously against the IBF and WBO finding their way into the rankings published by mainstream boxing media or being name-checked by TV commentators. Now some are inclined to reject the alphabet firmament altogether in favor of a shiny, new, "better" thing (ie TBRB), but...unless that sentiment catches on like wildfire (and in nearly a decade it hasn't, really) there will continue to be the 4. Maybe it'll dwindle over time if the WBC or WBA swallow up the lesser pair in mergers or the business model of the latter simply becomes unsustainable, but I don't see the ABC era concluding or us having fewer than four sanctioned world champions in each division at once (that is, real champs per sanctioning body per division - not getting into all this regular/super, interim, Gold, or franchise hokum) any time soon.
The WBU (World Boxing Union) made a splash from 1995-1997 when they recognized Lineal Champion George Foreman as Heavyweight Champion when no other major body did, which meant they were the only ones at the time, who recognized the real Heavyweight Champion of the World. Source - Wikipedia: World Boxing Union "The World Boxing Union was a boxing sanctioning body. The original WBU was founded in January 1995 by IBF European representative Jon W. Robinson. It sanctioned boxing with various promoters worldwide. Founded: 1995 president: Torsten Knille" Google Question: ("Whatever happened to the WBU?" "The World Boxing Union, Inc. (WBU) was a professional boxing sanctioning body based in London, UK, a long time ago. After all boxing sanctioning contracts were fulfilled, the UK company became dormant and eventually was dissolved."
Oof. That's funny, but super unfair to Schmeling. The other two guys, Haymann and Mueller, were actual, dyed-in-the-wool Nazis (the latter died battling for the cause a day before Hitler, and the former wrote a propaganda manifesto encouraging German youths to pick up boxing to serve the aryan masculine ideal and bludgeon ubermensch ) but Max? Nah. He wasn't down.
I'm guessing in 99 when a shot Berbick won the title it pretty much devalued it. Kirk Johnson could have easily won the title if he chose to at that point.
The Langford true lineage is still going to this day but is hardly talked about Dempsey got the lineal title in 1921 from Carpentier not Jess Willard!