When I was at school, there were three TV channels and not many more radio stations. Television started in the afternoon and stopped at 11 pm (with the national anthem). News came from bulletins scheduled at fixed times in the day, and from hard copy newspapers printed overnight and delivered in the morning. If something really exceptional happened, programmes might be interrupted for a 'News Flash'. This happened about once every five years.
It's different now. It's a bit like food. In the early twentieth century, many people in Britain were made ill by not having enough food to eat. In the early twenty-first century, almost nobody in Britain does not have enough food to eat, but many people are made ill by only having bad food to eat. Rickets doesn't kill people any more; obesity related illnesses such as heart disease and diabetes do. So with information. There's no shortage of it, but it isn't all good, and if you consume the wrong sort it can damage the health of your understanding. So you need to be discriminating.
Social media is a wonderful invention for certain things. It is a superb tool for connecting people with like minded interests, for organising people, and for disseminating information. I'm not convinced that it is very useful for informing yourself about the world. There is a natural tendency for it to form into bubbles of like minded people who simply reinforce one another's prejudices without being challenged. The brevity of the medium also means that it is very hard to develop arguments with the length and complexity necessary to understand them properly. The anonymity of the medium means that anyone can post anything, without having to take responsibility for its accuracy or fairness. Moreover, there is substantial evidence (for example, from the Brexit referendum and the US presidential election in 2016, and now with anti-vaccine propaganda) that social media can be manipulated in a very sophisticated way to distort the outcomes of popular votes or to spread malicious and false conspiracy theories.
The advantage of what is sometimes dismissively referred to as 'the mainstream media' is that it is more accountable, and more controlled. Anything printed in a newspaper or broadcast on a mainstream TV or radio channel will have been fact checked and edited. That does not mean, however, that they will be free of bias; part of being a good debater is being able to detect and take into account that bias.