> treating customers well would result in greater retention, which, in turn, would ultimately prove to be net positive profit-wise over time.

may be true in the past, but a business cannot scale up good customer service - it's at best a linear scaling, where each new customer costs the same fixed amount due to needing high touch/people to manage that customer.

With the internet, businesses have found scaling to work better by ensuring your fixed costs stay fixed even if you scaled up customer count - this includes support/call centers etc. Without doing this, the business cannot scale up exponentially.