One doesn't need to learn how to ride a motorcycle before learning how to drive a car.
Just because one knows how to drive a car, doesn't mean they know how to ride a motorcycle.
Those who know how to ride a motorcycle, and have operated motorcycles on city streets and public highways, will likely agree that what they learned about traffic, reading the intentions of other drivers, and having a keen sense of the surroundings at speed, with nothing but their leather and helmet between them and death... are skill sets that made them a safer, more skilled, more alert, and more in tune operator of automobiles.
So while motorcycle riding experience can produce better car drivers, motorcycle experience is not required to become a skilled car driver. I know drivers of automobiles who have driven 70 years and never once learned how to ride a motorcycle, and never once caused an accident or received a moving violation of any kind.
One can learn how to mig, with excellent results, including sufficient penetration into the base metal without burn through, including sufficient toe wetting and tie ins without dimension altering distortion, including porosity free beads of adequate leg lengths, and including sufficient heat management to reduce the HAZ or cause annealment... without ever picking up a gas torch.
The reality is that costs of oxygen and acetylene have skyrocketed, and the handling of these gasses in a home environment... from cylinder safety to hose inspections to valve and regulator care etc etc... may not be worth the investment of time, money, and training to become proficient in a process that one will not regularly use, only as preparation for a process that one might more readily use.
Forty years ago, wire feed welding machines were prohibitively expensive, and outside the reach of most hobbyists. Today, electrical welding, even with the cost of consumables, shielding gas, the machine, and the electricity to run it, can be less expensive per inch of weld than the cost of fuel gasses sold in the smaller sized cylinders.
One doesn't need to learn to paint houses before learning to paint murals. And vis a versa.
Mig welding has it's own layer of skills that need mastering, whether already skilled in OA or not. Sometimes, the skill set can be opposite of what applies to other processes.
Don't feel as if you have to acquire an OA rig first, and then all the experience to use OA, in order to "really" learn how to use a MIG welding machine. That way of thinking is an unnecessary discouragement to folks who are excited to learn with what they have, or what simple set up they can afford.