A specimen to be examined under the microscope is first placed on a glass slide which in the case of the cheapest instruments is then secured to the stage of the instrument by spring clips. When the slide needs to be adjusted this must be done manually, a process which can be somewhat irksome particularly for beginners who are trying to cope with so many other new things. More expensive equipment has a mechanical stage which is moved by two control knobs. And worth the price if you can possibly afford it. Objects to be studied need to be illuminated.
Daylight is no use at all.
A separate lamp is effective enough and is the cheaper option though again more trouble to use as it needs more careful adjustment than the more expensive alternative which is built-in lighting. If one has a room where equipment can be left set up then built-in illumination is not so important. Those of us without such a facility appreciate the convenience it affords. It is no use having an instrument which is too much trouble to set up and use. With cheaper microscopes the whole instrument tilts forward including the stage when one needs to use it, at any rate from a sitting position.