The last thing I want to do is comb through 23 lines of code

It's HTML. I just did the same thing on a project and it took less than 10 minutes to add, customize and style the form. In fact, some of that you could remove if you want a minimalist form without the labels and instructions. It most definitely took you longer to find another service and signup (not to mention writing this article.)

You’re really telling me to “View Page Source” in the answer? 500+ employees and that's your direction?

They're telling you to view source because (1) those forms are customized to your MailChimp account and (2) they're speaking to a developer audience that shouldn't be afraid of viewing a little HTML.

MailChimp has a variety of other ways to connect with your website including official and unofficial integrations for every major CMS. For most people: they install a plugin, paste an API key and move on with their life. You wanted to set things up manually and then complained when you had to do some work.

MailChimp is far from perfect. I've worked with most of the major email platforms (including Sendy+AWS SES) and MailChimp has been the best I've found overall. This takes in to account features like automation, list management, tracking and deliverability. If I had one major complaint with MailChimp it's the price for large email lists.