Unless I misunderstood what you mean, here :)
Yes, it is - there's a lot more non-techies than there are of the other kind, so it makes sense that you focus your efforts on the larger market.
As for the whole "language that beginners use to learn about programming", do you mean Python or Java? PHP is everywhere but the last I checked, Python and Java are the teaching and taught languages.
PHP itself is designed to get things done, not necessarily elegantly. For all it's problems, it is a workhorse and blaming the language for what the users have done is just wrong. Programming languages are like hammers and should not prevent one from doing something stupid or irresponsible. Doing the smart or right thing is the responsibility of the user.
I don't want to spark some sort of war on what language beats up your language. So I wont. Besides I don't think something 'being everywhere' makes it good. By that standard lots of things in this world are good.
PHP is exactly what you say it is with regards to being similar to a workhorse. It is a tool for programmers who like to work very hard to achieve something that a harvester could do a lot quicker and more efficiently.
Alex Munroe explains what I meant better than anyone I have seen. It is a great read. Also if you like PHP. http://me.veekun.com/blog/2012/04/09/php-a-fractal-of-bad-de...
He does not bash PHP, he explains why he thinks it is the wrong tool for the job. Interestingly, he also uses the tool analogy. We are all so predictable :).
I go to any $5/month host, check "install wordpress", and it's done. When Clojure CMS/blog apps have even 1% of the installability (as in, ability to be installed) by non-developers, perhaps they'll have a fighting chance.
I say this as someone who develops Grails apps all day long.
That is a function of popularity, not language. If some blogging app had a userbase the size of wordpress's, it wouldn't matter if it were written in PHP or brainfuck, shared hosting providers will set it up. This is why appealing to techies makes sense. They will be the ones setting it up in the initial "its not popular yet" phase, and if they don't use it, it will never get off the ground. Once they start setting it up for their friends/family/etc, a few companies start offering it as an option for their hosting. Then a few more, and it snowballs as the app gets more and more popular. Trying to start from "use PHP so end users will use it" doesn't work, because installing a PHP app is just as hard for them as installing anything else.
Keeping JVM engines going, and keeping a lot of compiled apps in RAM, on the offchance that someone makes a request, means fewer apps/sites can coexist on the same hardware. My $5/month PHP plan (hypothetical - I don't have one) - only compiles/executes the PHP when the request is made. If no one requests my site for 3 days, it's all just sitting there, not using any resources.
Until there's another technology that follows a similar model (or something else which provides good economies of scale for hosting providers), PHP will continue to dominate large segments of certain problem spaces.
Anyone that only has PHP likely also doesn't have their PHP/MySQL updated to the point that anyone should trust them.
apt-get/yum install ruby rubygems
gem install railsRails is a great platform for building a custom web app, but it's a terrible platform for building an open-source blogging platform. It simply moves too quickly and breaks things too often to be useful for the demographic that uses WordPress.
When you're talking about web code with such an astronomical deployment to developer ratio, the advantages of PHP are magnified by several orders of magnitude. Even the perfect WordPress replacement written in Rails with elegant, featureful and performant Ruby code digitized by God's own hand is by definition a niche product that can never hope to compete meaningfully with WordPress.