For rapid development of our UI Controls,
These company who provides 3rd party controls like infra and dev express, focuses on windows ui control development.
They provide more advance and easier controls compared to what we can develop, so we focused more on the application development.
3rd party controls like infra is a lot more easier to use and advnace compared to the controls that are included in the .net package. It has a lot of features that gives you more control on ui development.
Compatibility issues on different OS is not a problem with infra. because it can support themes