It may simply be that you are, quite literally, reading something into a post that was never intended. This is why the environment here is structured. Community members are given permission to start topics in conferences. Staying on Topic - One might think this is easy and obvious, but it is sometimes hard to do. It is not altogether a bad thing and can often restart a moribund topic, but can best be minimized if new posters make sure to read several posts prior to the last one in order to make sure they know what is under discussion.
Commercial spam is unacceptable.
Discussing a commercial product or linking to a commercial site which has relevance to a conversation is not spam. This is the easiest thing to do since it requires no knowledge of html. Those who know html can use fancier methods to do the same thing. Links are used when the writer wants to refer to what is on another web site, perhaps a page from ALA or something on the writer's home page. Linking is a very useful feature in conferencing since it allows several people direct access to the same information.