. In my experience, 2012 and earlier MTB are idea kit bikes.
Just a caution on this - older mtb parts can be expensive and surprisingly difficult to repair / replace.
As an example - my ? 2009? Trance rear shock died - it has a pre metric fox shock , so the lower eyelet is too large to use any modern replacements. I had to machine up bushes for the frame and custom spacers so we could use a " normal" lower shock bolt. We were a fraction if a mm out on the machine work so I'm left with a subtle but still annoying level of slop in the linkages now.
We have a similar vintage specialized , the brakes are weird rebadged sram - it was a nightmare trying to figure out what model they were so I could replace the pads, and they are evil things to adjust. Realistically I could just replace the whole unit fir a few $100 , but where do you stop sinking $ into older bikes?
Even getting replacement tyres can be challenging - you can't just wander into the lbs to grab a 26x2.25 ....and you definitely can't be fussy about what tread pattern / compound you prefer!