“But please note that eBooks.com uses Adobe DRM to protect most ebook files, so the device, or the software running on the device must be compatible with Adobe DRM. If you'd prefer to obtain your books without DRM, you can browse our DRM-free section.”
Yes, unfortunately this is the case (I work for ebooks.com). Most publishers require us to use DRM and Adobe DRM really sucks, but there isn't other options out there and we don't have the resources to make something better.
We focus quite a bit of effort on educating publishers about moving to DRM-Free as it makes everyone's lives easier and from what we've seen increases publisher sales numbers.
“But please note that eBooks.com uses Adobe DRM to protect most ebook files, so the device, or the software running on the device must be compatible with Adobe DRM. If you'd prefer to obtain your books without DRM, you can browse our DRM-free section.”
https://support.ebooks.com/hc/en-gb/articles/214119286-Guide...