Pretty much the reason...take a look at Marlin Owners...its a total clusterfoobar, huge site, lots of stuff, only basic organization...
great info, but you really haveta DIG for it!!
Then you look at Rimfire Central, and it is easy to find ANY info on there FAST!!
You go directly to your category and start soaking in the info!!
This is particularly helpful as Marlin changed very little over the last 50 years in any category...
things that work for antiques often work for newer rifles...the biggest changes recently being:
The T-900 trigger group for Bolt actions, which was bettered by...
the XT Trigger Group, which fits on 25N's, 800-series, and 900-series bolt action rifles...same for the stocks...
and the Single-Shots are mostly derivations of the bolt-actions in existance...
The Semi auto 60, 70P, & 795 are all based upon the same action components...
and thusly switch a lot of stuff back & forth...trigger group is the same square-back model...
the 99-series (including the 989/989-M2/995/etc) are the same as Old Model 60's with round/egg-shaped trigger guard ends...
Lever actions can be simply divided into Centerfire, 39-series, and Levermatics...
really few major changes since 1883 other than that dadblasted rebounding hammer and the addition of the cross-bolt safety...
the 336 & the Big Bore Marlins (45/70 & bigger) all share the same mechanism down to the lever loops...
The Levermatics are the pinnacle of short-throw modern lever-action...yet even though superior, never found a comfortable home with consumers...
And the venerable 39/39A series, which are not only the longest continually produced lever-action,
but the strongest rimfire action made today...even by Remlin, which is doing a decent job on 'em now...(at least as good/better as the CT 2005-2011 ones)
And that's why its better to separate it all now instead of having to do it Later and do Ten Thousand Posts placed in their own branches 
RFC had to do that, and it was a Herculean Effort by several Moderators...but it sure paid off!!