With the exception of the Halson inversions, Mr Dirt PBF, and the DuroTrak forks in the early to mid 90s, all inverted forks have depended on not just disc brakes, but also oversized hub axles of some sort to compensate for the absense of fork braces. The last Marzocchi ones were the shiver SC's and they ran 20mm bolt-on axles. The Maverick's depend on a 24mm axle. Mountain Cycles Suspenders had dedicated hubs with 12mm axles (bolt on with bullseye hubs in 1989-91 and later basically an combo thrushaft axle and qr with pulstar hubs beginning in 1992). This is in addition to massively oversized upper stanchions and sliders that themselves were typically as large a diameter as the lowers of many regular telescopic forks were of the time. All these extra large parts add weight (unless you use super thinwall construction like the mavericks and hanebrink forks, which are also super dent prone), and relative to the weight of the forks, convention forks tend to be stiffer. The only advantage to the inverted setup is the reduced unsprung mass makes the forks react quicker to impacts. So you take heavier forks and combine with heavier hubs, and you end up with something few riders really want or need.
