I wasted hours on the phone to a bank just yesterday, and as the architect of a major crypto exchange (last gig) and international entrepreneur spanning China/non-China (current gig) have had ~maximum scope for degrees-of-unbanked both personally and as a business, experiencing related pain points across multiple jurisdictions as well as living the here-now China 'dream' of 100% mobile money.
At a high level, while banks theoretically primarily provided the 'don't get mugged' service in the past, presently they also importantly provide de-facto services like: taxation and AML choke point for government, identity verification and re-authentication services, lost funds debugging, due legal process for dead and mentally unwell people, bridge to third party settlement networks, evidence-of-funds, evidence-of-income, capital provisioning and macro-economic policy implementation partner with respect to state-usury and inflation, etc.
Even if you don't require the "don't get mugged" service (eg. your superyacht is packed with bullion and you travel with a private army), you may find it hard to deal with others (eg. how do you pre-pay for mooring locations, new army recruits, satellite telecomms services or carry permits before you moor the yacht at your tax haven/island of choice?). Using a more down to earth example, you'll find it hard to purchase tickets to travel, food to eat, or restore access to funds if you forget your crypto password, have a stroke, become bedridden, lose your stuff in a fire or get mugged. Similarly, getting a loan or immigrating will become impossible (no proof of income/funds). Excusing the tongue in cheek examples, removing banks thus causes social fabric issues, despite the fact that everyone hates them.
IMHO it's becoming globally more viable due to new technology (mobile money, statecoins, etc.) but replacing the bank with the third party crypto-exchange (crypto-liberatarian dream at the facade, heavily yoked to techno-capitalism and existing state bank control mechanisms behind the scenes) or directly to the state (digital yuan/statecoins) is just shifting rather than solving the problem.
As it seems you are wondering about interest rates, that's less about banks (FWIW I used to share a house with someone on the interest rate committee for the Bank of England) as they basically echo the government numbers (and then add some). Interest rates at the national level are more about macro-economic policy which is political, and a case may be made that they are a requirement from governments in turn for participation global capitalism and real world supply chains for societies that rely on global resource extraction. Put simply: if you want a functional post-industrial society currently the only way to achieve that is through global trade, and if you're going to join that bandwagon you have to deal with inflation as a matter of course. Of all the available political macro-economic levers, central bank interest rates are among the least disruptive and most timely we've come up with. After all, if you don't like it, change currencies.
In short: if you're mostly worried about bank fees, change banks. If you're mostly worried about interest rates, change currencies or get out of fiat currencies entirely and in to a broader portfolio, eg. real estate, stock, commodities. If you want to reorganize society to libertarian ideals and plant a vegetable garden, better get ready to give up all your technology and prepare for political and economic irrelevance... and you might still get mugged for vegetables.