One example surrounded by many other pieces of hardware that don't do this doesn't do much to solidify your "cannot" absolute.

Edit: Your second link makes it pretty clear that it's not Alexa's lack of profitability that seems to be the issue with regards to ads playing between songs. Apple Music has a free, ad-supported tier - meaning that on whatever device you use it on, you'll hear ads. If your Alexa is set to access your ad-supported Apple Music account, then of course you're going to hear ads.