Regardless of what is written on paper and/or on a website: different requirements or detailed documents can be requested at any time, depending on the processor, and the processing times can also vary. As far as I remember, it took 8 to 10 working days and two requests. In Germany.
No, proof of a bank account was not necessary. In my case, the certificate from the German embassy was completely sufficient to show that the income limit of 65,000 baht/month was reached or exceeded. However, like many things in Thailand, each immigration authority handles this differently.