I have an actual technical question related to this.
Consider the situation of EMC testing. When a charger ships with the product, the EMC test is done on the combination of the power supply and the product. If no power supply is shipped, the manufacturer is free to choose anything that is within the nominal specifications.
More than once in EMC testing changing the power supply resulted in the difference between passing and failing, sometimes by a quite large margin.
Therefore, it's likely that as manufacturers continue to not provide a power supply, then they will test with a top-quality "quiet" supply that give them, let's say, 10dB margin in some EMC test. If the top-quality supply sells for $20, while the cheap ones are $2, it's likely that a fair percentage of customers will get the "equivalent" cheap supply. This is already a dynamic with cell phone chargers.
What does this mean for EMC testing?