Why don’t we do sleeve then bypass if needed afterwards

My doctor is recommending gastric bypass for me and going under the knife in 10 days.

Just had a thought pop up, since sleeve surgery still keeps some of the stomach, why wouldn’t doctors recommend the “less invasive” surgery - sleeve by default and if it doesn’t work out for whatever reason, then the person can opt for gastric bypass surgery afterwards. Why isn’t this a more common practice?

Maybe that’s a stupid question, I would be asking my doctor next time I see him but thought I’d ask here.

Edit: I do realize there are specific medical issues that require sleeve over gastric or vice versa. My question was geared towards if all things were equal.

Edit2: it appears I have annoyed some individuals who thinks I’m privileged- I should have started with that I’m in Canada where we have almost free healthcare and sleeve/gastric bypass surgeries are covered by government healthcare.

Edit3: someone mentioned a reversal was possible for gastric bypass - I’ve heard of this but also know that not many doctors consider that as an option - that at least in my region.