I worked at an agency for almost six years. In that time, I created only a handful of static sites. Part of this was because the agency had a custom content management system. The other part was an unwillingness to give up "dynamic" websites.
tldr; I've created a website to aggregate resources for agencies and freelancers looking to branch out into the JAMstack. It's called MyClientWants.com
This was definitely an relevant concern when I started, but by the time I left to start my own business, it was no longer valid.
When a client couldn't use our proprietary CMS, we'd often use WordPress. Our server language of choice was PHP, so this made a lot of sense. WordPress comes with a lot of baggage. It also is it's own style of management. We used "WordPress-specific" hosts to avoid putting a security vulnerability like WordPress on our main application server.
As developers came and went, we lost most of our WordPress knowledge. Legacy clients still using WordPress became highly problematic.
JAMstack sites are built out of HTML, CSS and JS. Most developers I would look to hire at an agency would be proficient in these. That means that most could figure out how to modify a JAMstack site. Legacy codebases become less problematic.
If JAMstack sites are less of an issue for legacy sites, why do agencies -- which tend to have a decent amount of turnovers -- eschew them?
There tends to be a stigma around "static sites." Most clients have a decent number of requests that seem problematic for static sites at first glance.
Clients want contact forms, e-commerce, a CMS, comments, and more. Unless you've been paying attention to the JAMstack trend, you may not know that these are all possible on a static site.
To fix this stigma, I'm putting together a resource center to help developers figure out even the weirdest of client requests. Let's face it, clients have varied and complicated needs. Let's make sure the JAMstack is up for it. Let's make sure agency developers and designers know of all the tools.
Head over to MyClientNeeds.com to view the resources I've compiled so far. The current categories are Forms, Content Management, Integrating with APIs, E-Commerce and User Generated Content.
I've got a couple dozen resources listed, but I plan on that growing quickly. If you have any resources you want to share, you can post an Issue on the GitHub repo.
I hope this helps folks discover that the JAMstack is the future and they CAN take part in that future today ... even when working with clients.