Bit of an unrealistic comment, this might be a choice you can make for yourself, but most people don't live alone and share their internet connection with others – I doubt telling your partner or housemates to get a new bank because of the DNS ad blocker you set up on the network will go down well.
Ad blockers pretty much all rely on community-maintained block-lists, there are always going to be mistakes in those that break some sites, or some sites might not act well when unable to send ad/tracking events. I recently had an issue booking a train, which was because of this, turned off the ad blocker and it worked fine, not something that's as easy to do with network level blocking, especially if it was set up by someone else and you're not a technical person. Not booking the train because their site is bad is not a realistic option.
Aren't banks sort of the poster children for legacy practices though? Only works with this or that browser, here are some weird password rules, yes I have an SVGA monitor, no I can't search older than 90 days, etc. I'm used to turning off my modern expectations and just getting into the 20 years-old flow for the time I'm logged into the average bank. No, I don't want to switch banks (where my mortgage and dozens of ACH linkages are set up) to have better ad blocker compatibility.
They aren't using advertisers. They're incorrectly* using user behavior instrumentation for diagnostics and anti-fraud, especially blocking on login if tracking is disabled as they are trying to prevent credential stuffing bots.
* Bug, or feature, many fail if the tracking is blocked, due to other code that assumes it's there or depends on it. They fail closed instead of fail open.
Sorry, but I laughed at your comment. Didn’t mean to be disrespectful, but it is laughable.
Banks and other financial institutions have a duty to prevent fraud and their malicious actors. Could they do better, yes. They still have a duty nonetheless.
Adblockers do more than just domain blocking, such as anti-fingerprinting, bot detection—which includes a lot of, sadly, invasive checks against the browser.
UBlock has annoyance lists, tracking lists, and others and others…
From what you’re telling me, you’re wanting a bank that’s protecting their clients or at least attempting to. Ooookay