No way, building a custom CMS for a site which would have always been a good candidate for an off-the-shelf CMS is just as bad of an idea today as it ever has been.
> As developers, we are trending away from the one-size-fits-all CMS and into specialized categories of CMS.
Most of the sites which would typically get built on Drupal (and especially Wordpress) aren't owned by developers. Further, these owners probably don't even have a developer on staff or even on a maintenance retainer. Many of these sites are setup by relatively non-technical users. Many of these sites are setup by a developer the owner has paid and then that developer is out of the picture to be run by the owner.
Even if you are a start-up building your own web app, it still often doesn't make sense to build your own blogging system. Rather, you would get your first version out the door ASAP, throw your blog up on a sub-domain running Wordpress and then maybe down the road figure out something different.
Do what you want for your own site. But when you are doing something for clients who don't have a tech staff, it's not about what the developer wants.