Patents protect ideas and the use of these ideas. If you own a patent protecting an idea you have a monopoly for as long as up to 20 years in some countries. No body may use your idea without your consent. In order to use your idea others will have to license your patent.
Having a monopoly on an idea seems to be a good thing in order to protect inventors. There is however one problem and that is that most ideas are not that useful unless you combine them with other ideas into a product that can be used. Products that can be used like a cell phone or a web browser contain many ideas combined into a product. A lot of those ideas will be patented by others. Having to license these patents can be to expensive for small companies to start a profitable business.
When a small company launches a product based on a patented idea of their own; they risk a law suit if others suspect that they are violating one of their patents. Even if this turns out to be untrue the cost of a law suit can be devastating for a small company. Besides suing you as a company they might even consider suing your customers using the product.
Due to the large number of patents and the language used to describe them it is difficult not to violate someone's patent unless you are a lawyer with a technical background. One way to settle a patent violation would be to cross license your patent to the parties involved. However this is not always feasible when you are up against a multi-national with a large patent portfolio in your area of expertise.
"I don't like the idea that everything worth coding might already be patented or soon will be patented."
Patents should protect products and not ideas in those areas like software development where many ideas need to be combined to create something useful.
"If people had understood how patents would be granted when most of today's ideas were invented and had taken out patents, the industry would be at a complete standstill today."
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