There is no general standard
There's people who will swear by pretty much every idea out there, so who's right? Everyone or No one (depending on how you look at it).
There's basically 3 routes.
1) Raw PHP, quick to start, but can quickly become messy and unwieldy if the site is large. I usually go this route for microsites, as it's the fastest to throw together on simple projects.
2) CMS platform (this is what I call them, they go by many names). Applications like Drupal, Joomla, Wordpress, oSCommerce, vBulletin fall into these. They are pretty much totally independant ecosystems with various support from their community. They are the least flexible to work with, but offer the greatest functionality for time spent (as long as you don't deviate too much from their intended function).
3) A PHP Framework, there is a huge variety within this, but generally frameworks fall into two categories, Glue and Full Stack. Glue is less organized, closer to #1, while a Full Stack is closer to #2 in that it offers a much more robust feature list, but at the cost of flexibility/ease of use. For a wide variety of projects, this is generally the best option, as it's a good balance between flexibility and code reuse, but it's also more difficult to use than #2.
So in summary, the easier it is to use, the less functionality it generally offers as well as easier to disorganize.
It's simply a matter of personal preference as well as dependent on what sort of projects you do.