The easiest way to understand the issue is to consider cooking.
A chef can’t sit around and think up recipes and file thousands of patents. We explicitly agree in the law that it would be incredibly backwards negatively affect society if chefs got exclusivity on recipes and could sue home cooks for being creative. And chefs are still thinking up new recipes and using them in their restaurants because unique meals and flavors offer a competitive advantage. The reward is that you can keep your profits in our capitalist society. See Coca Cola and KFC. You have to use your knowledge in a novel invention to benefit.
In the same spirit, it’s not wanted to have people sit around and ideate about which instructions, and in what order, when fed to a processor machine, make it do useful things. Thousands of people program processors every day and we don’t want them getting sued because someone else figure out an efficient way to reverse a linked list. You have to run a software service that provides value and get people’s money that way.
Even if we concede that patents are useful in their intended purpose to protect actual manifest inventions, not just ideas (patent office is supposed to require a prototype invention to be registered with your patent), that’s certainly not what patent trolls are doing and that’s not how the majority of software patents work.
For the purpose of discussion, to get close conceptually to some sane type of sane SW patent scheme you’d have to 1. make a linked list reversing library, 2. register the complete prototype source code with the patent office, and 3. be actively maintaining and selling your linked list reversing library for your patent to even start to hold water. But even then you’re running up against problem that software is purely algorithms (just like recipes) and those aren’t even originally patent-able.
Apple can’t patent an “object oriented operating system” unless they’re offering that system in isolation and as a whole to consumers for use, which they’re not, but someone at the patent office got tricked into granting them a patent. Patents are supposed protect the inventors of complete products, not tiny building blocks of knowledge (algorithms). The “patent hate” is because despite the arguably good initial conditions, the patent system has been abused by greedy people who are not benefiting society in any way whatsoever. And you should be infuriated by that.