Agile is iterative, fast and flexible.
People start preferring agile methodology a long time ago.
It provides developers and designers more freedom as they work on individual modules.
As an example, waterfall for many decades was the best in the field and It is a software where you could be building something that was conceived several months in the past (and it may not even be relevant anymore).
It was a linear approach full of restricted development, which your projects were also affected by it.
In the past several years, people started to move away from waterfall model for a various number of reasons. Basically, it wasn’t flexible enough.
Agile methodology aims to solve many of the problems that software teams encounter using the traditional waterfall methodology.