My own opinion of why the cylinders crack at the tube base weld is because of "mast side sway".
The mast assembly has play in the mast trunnion bushing and mount clamps and this side sway tries in effect to break the tilt cylinder when stressed in that direction.
The tilt cylinder mounting pins prevent any sidewise stresses from being applied to the cylinder in the directions that the pins are free to move, but there are no pins or "give points" to stop the sidewise stresses of mast sway from being applied to the cylinder.
I believe that the sidewise stresses of mast sway weaken the weld enough that a crack begins to develop in the weld.
The crack then begins to spread below the actual surface of the weld and you never know where the crack will finally break through to the outside to reveal itself as a leak.
And rest assured, whatever small looking crack you actually do see on the surface, is only just that.......the portion of the crack that finally broke through.
I have welded literally hundreds of these cylinders on various Toyota, Komatsu, Mitsubishi trucks over the course of about 25 years.
I know from first hand experience that in many cases, the actual crack usually extends halfway (or more) around the weld circumference under the surface by the time it manifests itself to show as an oil leak.
Certified weldor? Yes I am.
The only reliable way to weld repair a cracked cylinder is to completely grind out, or otherwise cut out the old weld so that all material involved in the crack is removed.
That's not all there is to the process but I'm not going into a lot of extra detail about it unless there is a specific request for more.
Some people have blamed the cracking cylinders on "poor welding" by the cylinder OEM.
But I have doubts about that being a reason as cylinders I have welded (that cracked again later), did so only after approximately the same amount of time as it took for the OEM weld to fail. I have had some cylinders that I welded that have not yet (to my knowledge) cracked again.

There are likely a few factors involved in why some companies seem to have higher rates of tilt cylinder cracking than others, but I am betting that these factors result in a lot more brutal sidewise forces caused by mast side sway being applied to the cylinders than by hydraulic forces due to design or operator habits.