Jake, this is a great point. Your friend is right that some people just want to get their book “ready” for (self) publication, as in eliminating obvious errors, but if that’s not really your jam then I think it’s a good idea to downplay that on your site. If you want to work with writers on becoming better writers, versus just prepping a ms for publication, then I think it’s very valuable to signal that in the way you write your website copy, etc. (which it sounds like is what you’ve done).
As you say, growing in skill and wanting to publish/get published aren’t mutually exclusive, and it’s always great to have a range of services you can offer (such as query letter critique), but it’s also incredibly helpful if you are clear to yourself and others about the kind of work you want to do.
If you want to be able to offer other services to help people grow in craft (at a variety of price points to deal with the fact that people have various budgets), you could think about offering coaching or ms evaluation, where you’re not doing a full dev. (Less time-consuming so less expensive.)
If you’re not too much of an introvert (I know many editors are), a great way to start the shift to paying work is to hang out where local writers are–writers’ groups, local workshops or conferences, etc.–and get to know what their needs are. You won’t necessarily turn a contact into a client but often such contacts will spread the word.
Also, ask the people you’ve done free work for if they would provide a testimonial and/or a referral–it’s so hard to ask but people are often very willing to help, they just need to know what you need.