When we talk about cross-platform development, I think it is getting better everyday. It became super easy nowadays to have one application be deployed in multiple environments (web, mobile, etc...) and increase reusability of components built along the way.
So your argument would be one of economics? It's now cheaper to produce the same application on web, mobile and others by reusing components, rather than 'handcrafting' the code for each platform.
Is this a common pattern for all of the frontend SPA frameworks? How often does that cross-platform development get used (any idea of percentages per framework?). What's the overhead if any?
Speaking briefly as a user, I find a lot of the desktop versions of SPAs to be resource hogs - Slack, for instance. Is this getting better?
But web exists on mobile and desktop. It's been easy for a long time to deploy the same stuff to mobile web and desktop web. What hasn't been easy is designing good experiences for the same application across dramatically different contexts. What hasn't been easy is optimizing the same code for dramatically different contexts. I'd argue neither of those has changed much.
In fact, I'd argue that some things devs love about modern development have made those harder.
Obviously there are some specific stand-out projects directly addressing write-once, but have they helped with those two or hidden them under the rug? (Probably varies.)
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