magnesium oxide, colon cleansing is fecal impaction theory a whole lot of "crap"?

What I don’t understand about the alleged poop build up problem is this:
Wouldn’t doctors have mentioned this – after all it is really detrimental to your health it it’s true, right?
And also, ever had a colonoscopy? You have to drink that awful liquid that tastes like lemon furniture polish: do you recall what happened next??? Yup – all the poop came out. And then you had the colonoscopy. The doctor has to look at your intestines, and the intestines have to be clean so all the poop did come out, right?

Just my opinion. I think there are a ton of money-making schemes out there that are potentially harmful to our health
Do you think the whole "colon cleansing" thing is “crap”?
Are you going to find poop in your system that’s been there for years?
Isn’t a laxative going to do the job, which is get the poop out. No matter what the laxative is, it will get the poop out.