As a frequent SEO client, my perspective is that these packages that offer x articles, x links, x posts, etc. are not very attractive. Each site is different, and throwing a bunch of resources into SEO is usually not a good way to do things. Some sites need to focus on inbound links, others should optimize content, and there are so many factors and moving parts.
The SEO teams that I use have more a consultative approach, they look at each of my client's sites and prepare a strategy, a well thought out keyword list, a bunch of recommendations that are specific to the site, etc. So, on their website they don't really cite 'packages' as much as they talk about their results, and how they create an individual strategy for each clients.
I do agree, though, that optimizing your own site is a great way to demonstrate your SEO skills. SEO is, obviously, a competitive category so when an SEO provider is high up in the SERPS for SEO terms that is pretty compelling