I have several thoughts about this, and I divide this question between the community and the Ghost foundation itself.
At this point, I see Ghost divided between developers and professional users.
Developers hate WordPress because it is complicated, and Ghost is a bliss to use. But they self-host and recommend self-host to new users (more on this later).
Professional users come from Substack, avoiding 10% in commissions while having a better product in Ghost. These users might use Ghost (Pro) or not.
My take on the Ghost Foundation
IMO, Ghost (Pro) is the best way someone can experience Ghost. It’s less trouble with maintenance and configuring Mailgun.
I don’t use Ghost (Pro) because I wanted to use a custom theme, and $25 per month was not an option 1 year ago, and I’m using a 3rd-party managed hosting because of it.
I want to reinforce the point that others make in this post: not allowing custom themes on the Starter plan is shooting yourself in the foot. For example, I’m spending $6 more than if I used Ghost (Pro) only for the privilege of experimenting around as a content creator using Ghost.
Another point, I think the Ghost Foundation could do a lot more to foster a community around Ghost. This forum and the subreddit lack some love for new users. Building a less technical community (I will repeat this point a lot) should be a goal for getting Ghost adopted by more users.
When I discovered Ghost, I was confused by a lot of things. Everything I read felt too technical, the site layout, the language, etc. I can imagine someone less technical quitting before learning how to enable a custom domain on their Ghost (Pro) trial.
I feel that Ghost needs more educational material with non-technical users in mind.
Turning back to the initial point of the discussion, themes need to be more customizable. Ghost themes aren’t that expensive when you consider WordPress themes are a subscription, and on Ghost, it’s a 1-time payment.
Needing to code to change a theme holds Ghost back massively. The homepage customization is also complex for someone that doesn’t know how to code.
My take on the community
There are more non-developers than developers in the world, but most of the Ghost enthusiasts and content creators are developers and talk to other developers. Especially when recommending hosting.
This isn’t a criticism to anyone advising self-hosting. Instead, I’m saying that advice without context isn’t the best thing.
If a person has to learn how to install Ghost and keep it safe, that won’t be the optimal experience. It’s not an optimal experience on WordPress, and it won’t be on Ghost.
Solutions and suggestions
My take is that we need more focus on non-developers and non-technical people. Without these users, Ghost will never hit its potential. Millions of users are underserved by using WordPress, but they don’t know better and aren’t advised better. The monetary incentive for affiliates to push WP products is huge because they can make a sh+t ton of money by recommending hosting, themes, and plugins. But the community cannot do much more against this other than keep supporting the Ghost foundation in development.
For Ghost to thrive, it would need more educational content to attract non-developers to use Ghost. That would lead to more developers creating software as they would have a bigger potential client pool.
Theme customization is optimal from a technical point of view. But it takes the ability of millions of users to get their website customized to their liking.
None of this is a criticism to anyone, it’s my opinion after lurking on this forum for a long time, writing articles, and making videos to help explain Ghost to new users.