I need help with this short passage

This is from a mock TOEFL iBT test, whose subject is about the argument of digitalization.The question goes as :" There are people who believe that computer brings about only positive effects, and yet there are others who think that there are also some drawbacks. Provide your opinion and state your points."

I strongly agree with the ones who believe that there are definitely some certain drawbacks computers can bring about. Although some people might think that computers only cause benefits, it has already been medically proven that spending too much time staring at the computer screen will definitely heighten the risk of getting Alzheimer's Disease. Another thing is, while we rely on the computers to perform lots of tasks in our daily lives, there is a potential risk of having our confidential files being leaked online when we make online purchases or use online money transfer services. Aside from the aforesaid facts, I personally think that being addicted to the computers will eventually cause people to appreciate the relationships between people less as well as to adapt to the mode of having most of the interaction with others online, which, needless to say, will make us become somehow socially inert in real life. I'm not saying that all of us should reject the use of computer or deny others' rights to use them, and I'm definitely not advocating some sort of anti-digitalization movement here. I'm only insistent that people should be aware of the pros and cons of the computer, and in order to keep us away from being diagnosed with the so-far incurable neurological disease and being a cold vault in real life, we should remind us to step away from the computers as much as we can

As I wrote the short passage above, several questions popped in my mind, as follows:1. When I refer to "the computer", am I generally indicating all the computers approachable to men? Or should I say "computers"(without a definite article) to indicate the same meaning?2. Should I hyphenate "online"? In which case should it be hyphenated and in which case should it not be?3. If there's ANY problem within the short pasage(I guess this should not be called an essay because there are only two paragraphs, right?), please do let me know. And if you think that there's any other point to be stated in order to suffiently support my point of view, please do name them, too!