Domain expertise is absolutely not a given. For example: I'd wager very few devs working on healthcare apps have any experience working in healthcare. Very few ad tech devs have ever run an ad campaign.

In regards to staying up to date on php. Surely best practices aren't changing very often? For myself, I look forward to some niceties coming in my tech stack, but I honestly care very little if literally anyone at my org is aware of them. We won't be retrofitting old code and using it in new code will come with all the little gritty interfacing with old code issues that always surface.

So why should I judge them on something that will have little or no impact on their day to day and when it does come around the people who do keep up are more than happy to show it off and evangelize?