IMF exists, because it benefits lenders. imagine country A cant pay back China. Now country A says, "we have no money to give you sorry!". but countries are not like people. A predatory lender can send out the yakuza to break some knee caps and take the tv and jewelry, but China cant send out the People's Liberation Army to collect debts.
Essentially, China lends money to debtors so they can pay back the original debts country A accrued. But like above poster noted, now the Chinese can start making demands on how Country A runs its treasury.
So you might think, well then IMF f@cking sucks, let's just getmrid of it. But what if country A goes bankrupt? Angry China might rattle her sabres, but economically destitute country A might also think war is the "only way". and often when country A goes bankrupt, country B also goes bankrupt. Because country B might do a lot of business with country A and country B's lender's also wont get their money back and merchants who used to sell stuff ti country A is also going bankrupt, because there is no more market in country A. Now country C might go bankrupt too, because country B went bankrupt and D, E, F, and G are all lined up to go bankrupt too for the same reason.
Then the chairman of the politburo in China wakes up one morning and read the headlines of Xinhua and it reads, "China also bankrupt". he is saying, how the f@ck are WE bankrupt??!! then his finance minister looks all disheveled and on verge of tears and say, "the currencies of countries A B C D E F and G are all worthless and all those mofos who we lent money to wont pay us back!m and they say they wont even buy any more Made in China toys, electronics, apparels, because they have no money."
Now everybody is sitting around sh177ing in their pants thinking, "why o why did we get rid of the IMF?". and these countries start waging wars with each other, because heck... they got nothing to lose but their lives. they are all angry and blaming each other and need to kill people to feel better about themselves.
The IMF is not the problem. it is the natural product of a system that has big problems.