My understanding is that part of the problem is that many banks do not provide that kind of "direct connect" functionality anymore. Some used to provide OFX but no longer do. Also, financial regulations aimed at "open banking" (like PSD2) bizarrely seem oriented towards enabling middlemen like Plaid. They don't require anything like "each individual customer must be allowed to access their individual data by using an API however they want"; it all has to go through a "third-party provider".

So the holy grail is really "Banks must be required to provide all customer info in a machine-readable format, via a programmable API, directly to their customers." :-)

You're correct here. The banks have limited who they are allowing into their systems more and more right now. We wanted to build direct partnerships with trading institutions to leverage their brokerages but they'd tell us to speak with their whitelisted partners like Plaid or a new (YC backed) incumbent, Snaptrade.