This seems to be a case-by-case/branch-by-branch thing; I have heard reports of people on tourist visa successfully opening a bank account, and other stories of them not succeeding. Seems to be more likely if you are not a US citizen.
For what it's worth, I don't have a bank account and get by on a GCash account (the local e-wallet , max' 50,000 pesos balance, 100,000 pesos/month transactions) and then use Wise to deposit/transfer my native currency into GCash, and a GCash card to get cash out of the ATM.︀ But it's too limited if, say, I was trying to build a house or do︁ something capital intensive.
The Philippines has pretty clear policies that , unlike most countries , you can stay there︂ a very long time and NOT become a tax resident. They don't care about your︃ foreign income, and are happy to simply have you spend your $ in their country.︄
What they don't like is when you take a job or open a local business…︅ anything that could be interpreted as competing with Filipinos in the domestic marketplace. I even︆ heard about a foreigner who volunteered to play piano in a hotel lounge for free︇ , he'd still be providing value to the hotel that they ought to be paying︈ a filipino to do, so it was considered too much of a gray area for︉ the hotel to accept.
And then you can get on a︋ plane, have lunch in Singapore or Ho Chi Minh or wherever you like, fly back︌ and you're reset to day zero, and can spend another 36 months. I know guys︍ who have been here almost 10 years on Tourist visas.