AE Basics: After Effects works with layers. If you want text on top of a solid you just put text on top of the solid. If you want to make that pair of layers a single layer then select them both and pre-compose.
Before you answer a question, it's a good idea to ask yourself what the person is looking for. I'm guessing the person was wondering if there would be a conflict of layer protocol or what text options would he lose by taking that action...basically, would it be beneficial or would there be constraints that would cause problems down the line....Your answer presumes the person is lucky he didn't electrocute himself turning on his computer
Is it possible to create a text on a solid layer? Just like it would be one picture.
the answer is Yes. you can add an effect called "Basic Text" to the solid. edit your text and check "composite on original"