The advantages of automated testing are perfectly clear: faster testing times, reliable scripts, minimal errors, and many other perks. While these are clear improvements, there are also downsides. For instance, automated testing requires a higher upfront cost than manual testing as well as coding knowledge.
Manual testing, on the other hand, does offer random testing and human perception, which is important for the UI of systems. Unlike automated testing, which would require time-consuming coding to fix any issues with the testing, manual testing allows for human flexibility to not be impeded by simple UI changes.
The truth is that while both automated and manual testing offer benefits and downsides, the answer is not either or, but both. A proper balance between both types of testing will cover all bases and provide much better results.