Take Y! SBC DSL. They use PPP over Ethernet (PPPoE). This has something to do with their provisioning and usage logging. I'm willing to admit that they know their business better than I do and there may exist reasons for using this that outweigh the "plug and play" ease of use that the system would be without it. But on top of all that, they require you to use their software to set the account up. They mostly ignore the case of using a cable/dsl router. The software setup is actually half a series of web pages, and half built into their software (if you know the right web address, you can access their sign up process at around stage 4). Part of their software then installs a whole bunch of Y! software crud including Y! Messenger, Toolbar, their own browser in the newer versions, etc. Courtney really appreciated all this when I did it with her work laptop last time (since I didn't have a Windows machine at the time to do it from). I don't need nor do I want all of this bundled crap. At least, after the annoyance of figuring it out, it actually worked flawlessly for 2 years.
At the new place, I got a Comcast cable modem instead. Mostly because SBC claims it takes a week to get DSL service, whereas Comcast offered installation on Saturday and Sunday. Comcast uses a system more like that used by hotels and other "sign-in to use" services where they intercept all web traffic (and block other ports) until you register. On the surface, sounds better than the software route used above, except instead of the simple web registration that you'd get in a hotel or anywhere else that used this method, all you get is a "download this software to register". Windows software, I might add. 22MB of download. The page uses relative URLs for images, so if you go to some url that isn't at the top level of a domain, all of the images in the page fail to load. And they don't use a fully qualified domain name for the download link, just "cdn", so that fails as well. Or maybe there was some other failure going on there, since it worked later on. If you pop in the CD they give you, it has the 22MB registration software on it. So, you pop it in and register, and away you go. They make you reboot your computer (which shouldn't be involved at all, I have a gateway router/NAT), and the modem, and bam it works. Except it stopped working 20 minutes later. Reboot the modem, it works again until I try it next, and then I couldn't get it to work until I called Comcast support, they had me reboot my computer, the router and the modem, and it works (and he was connected to my modem and didn't understand why it didn't just work before). I'm expecting to go back home tonight and find it doesn't work. And to top it all off, they replaced the rotating World IE throbber with the C in the Comcast logo. How nice. Luckily I don't use IE. Unlike the Y! crud, which I could uninstall, I don't see anything in the list of programs to uninstall to fix that.
You'd think a little bit of software to set your computer to use DHCP would be fine. Or even instructions. They have instructions on their site on how to set your computer to use DHCP (they don't call it that, of course). Can they really not have made whatever provisioning/registration/whatever crap done on their end?
In my old age, I'm beginning to be less and less willing to deal with all of this stuff.