Your business is growing, you're starting a new business, you're scaling a current company. These, among many other reasons, are why people seek out developers for web app creation. Some shops prefer to use frameworks such as Wordpress or others to build out web apps for their clients. Other shops prefer to build things from scratch. There's pros and cons to each approach that a perspective client should be aware of.
1. Time to build.
At first glance it seems to be a no brainer that a framework approach would yield a faster production process. However, in many cases, this isn't the case. Initial deployment of a framework may be faster, but changes and customization can take much longer in the medium and long term. That means if you want to make changes, add, or subtract from your web app you may face longer development times later on. For custom builds the development shop already knows the architecture of your web app so changes should be faster and simpler saving you money in the long term.
It should seem that many existing frameworks would be very scalable to meet your demands because so many people use them. However, that so many people use them can actually greatly hinder their scalability. These frameworks are trying to be so many things to so many different people, resources are drawn to features and pieces of your web app you may not even be using. With a custom framework all the resources are optimized and dedicated only to the exact purpose that it was built for giving you a scalable and performance focused experience.
While frameworks can be highly customizable, there are limits to what they can do. This can be especially problematic if you have legacy infrastructure and you suddenly need to add new important features. With custom software it's inherently, well, custom. The developer that built it will have enough knowledge of it's exiting infrastructure that new customized options can be added on in a meaningful way rather than bolted on.
In conclusion, there are pros and cons to custom software versus a framework that need to be carefully considered cases by case. If you're looking for custom software say hi today!