The soup can end of the pipe having the path of least resistance was the only lesson to be had in the powder/gas experiment. It was a directed blast the way it was set up. If a fuel/air mix has the correct ratios it will always ignite when provided an ignition source. The launch distance difference between the black powder and the gas was simply the difference in latent energy content for each fuel. Gas has more explosive energy than dynamite. No, you don't need compression to burn, but to extract the maximum energy from a motor fuel you do. Diesel uel is a great example. You can burn it but it performs best when under compression. Lots of other factors involved in using the stored energy of a fuel with compression only being a small part of it. The method the energy is channeled is a science of it's own.

Back to choke plates and holes. Note that choke plates without holes in them typically are not cut completely round. They will have a square cut section on one end to permit air to enter the carb.