This is very very simplistic take. And no, it is not the case.
1) Barrel pressure varies significantly over the length of a barrel. For 556 if you drill gas block at 7 inches you will have around 17000 psi, same barrel gas block drilled at 15 inches will bleed you gas at around 8000 psi. This is very significant difference
2) The length from the gas port to the end of the barrel defines your dwell time - time or amount of gas or force which will you transfer from the barrel to your automatic system. You can't just drill a gas port anywhere you want on any length of a barrel and expect same cycle performance.
3) Shorter piston requires gas port to be closer to chamber, requires you to handle way more pressure for a longer time, so if you are doing long barrel not only you deal with way more pressure but your dwell time is way longer so you have to sustain this high pressure in the gas system for longer time.
4) Over gassed system breaks parts, creates way more violent cycle and more heat. Everything is getting worse, like even erosion of gas port increases. If you have overgassed system and you have short gas piston rod it means that you need to vent a lot of gas at a significantly higher pressure much close to the user hand etc. Short rod is not just a free solution to a problem.
5) In a short stroke system you also do not want to have hefty gas piston rod because it is a parasitic moving mass, meaning its movement and inertia does nothing good for the cycling energy but creates more stress on parts when it stops both ways, shakes the gun and barrel more when it moves and so on. In a long stroke system this mass at least adds up to the overall mass of the carrier and conserves more useful energy for the cycle.
Overall it is an issue of technical expertise, time and funding. There is not enough time and money appropriate to properly solve this problem for the given volume of the Canadian market.
