Why do backpackers and travel bloggers always say anyone can travel ?

That's their job. Should they start every piece with a disclaimer that it isn't intended for the unprivileged or those with other responsibilities? Come on, man.

Of course, you're right. But it's also sometimes a case of priorities. Some people express envy of the amount I travel. But they live in bigger, more expensive homes, eat out 3-4 times a week (at more than $100 a pop), buy new clothes, pay $5 for a cup of coffee at Starbucks and some send their children to private schools. Cutting back 2 dinners out a week, or making their coffee at home  would pay for a nice trip! But I also know people with very little money who have managed to travel because they are not paying off big debts. You've exaggerated, too. A flight delay does not ruin anyone's finances- you just take a later flight. In normal times, you don't lose your job just because you missed the flight home - although you might lose a day's pay. 

I had friends in college who backpacked around Europe.  The scrimped and saved up for air fare, and in some cases, Euro-rail passes.  They pre-arranged for various jobs once they to there.  They worked on farms, in restaurants, small stores, that sort of thing, in exchange for a place to sleep, and sometimes, meals.  It's a lot easier to live cheaply in Europe than it is in the US.  And keep in mind, things are much closer together than here, and there is a robust public transportation system, unlike in the US.  If they didn't have a place to stay, they stayed in hostels for a minimal amount of money. 

A friend's kid recently stayed in France for 2 months.  He lived at a farm and worked in exchange for room and board.  He took the train to get around and had a very good experience.  Granted, there are a lot of privileged kids who get their parents to pay for everything, or are trust fund kids but it can be done cheaply.  

I'm not privileged, but I'm comfortable (and older).  I booked air and a hotel for the first and last night, rented a car, and drove all over, booking hotels for under $100 a night in various towns and cites in Portugal and Spain.  Some of the hotels were amazing, some not so amazing, but none of them were bad.