Can someone explain to me why the debt ceiling is so important and why its always the focus of every administration?

How exactly did nations of the past get over insane amounts of debt? And is it really such a big deal as to take up the entire focus of the nations politicians and their strategy? Seriously I scratch my head cause its mentioned like a incoming asteroid that can only be avoided if some bill or whatever is passed.

And for a financial juggernaut that has the worlds economy dependent on wall street why cant they just ignore it and suffer no consequences? Like if a man owns a well that is a towns only source of water but has a lot of IOUs to different townsfolk. Why couldn't he just ignore them when they ask for favors? They still depend on his well for water so they can't just refuse to deal with him and his giant castle with guards means you can't just grab a mod of other people ripped off and threaten or force him to pay back his IOUs.

Maybe I got this completely wrong but I just dont understand the dangers the debt ceiling poses