I think "side loading" (non planar loading) is a fairly common problem on a lot of suspension designs, but it tends to be more of a problem on bikes with a yoke extension on the shock. As mentioned above, the extra length of the yoke is creating more of a leverage arm acting against the seal head & piston which combine to provide the bending resistance on the shock.
The inline only has a Ø8mm shaft which is supported by a tiny guide ring & a 6mm long DU bush in the seal head. The piston itself is only supported by a 3-4mm wide guide ring/wear band. In other words there's not much support against bending when the shock is fully extended.
The first thing to wear on these shocks is the DU bush & tiny guide ring. It'll allow enough movement in the shaft to wiggle & weep oil. If it is left too long & too much play develops, the seal head starts exerting a lot more force on the inside of the inner tube.
The pic is of a Inline that came off a Enduro 29er (they seem to be the worse of the lot for some reason). Probably the worst case scenario where the seal head has flogged out & the piston guide ring has worn through the anodizing of the inner shaft & is wearing the aluminium away. The aluminium was embedded into the guide ring & the oil was blackened with very fine aluminium shavings. Most of the wear has occurred where the shock was at full extension.
Moral of the story - keep your eyes on the wiper seal where the outer tube meets the air can. Once that weeps oil, it's time for a service.