Most of them are worthless; of any given intern class at a first tier technology company (e.g., Apple), only ~1-5% will actually be offered a full time job.
Those 1% are worth every penny, but you simply don't know who they are until you give the entire intern class the opportunity to demonstrate their abilities.
They are almost never worthless. Small startups who are not experienced with interviewing may get a few bad apples, but companies like Quora (and the others on the list in submission article) don't make those mistakes. Sure, they may not all be Alex "Im-a-core-dev-for-Pypy" Gaynor's, but generally they'll be worth every penny of that 90k and another 90k more.
In my experience at Google, far, far more than 1-5% were offered full time jobs. Maybe my group just had above-average interns? But I don't think so. The intern hiring bar was fairly high.
Yeah, this is silly. The point of having interns is like 90% finding and vetting new employees. Certainly, not everyone will be offered a job, but if less than 5% of a company's interns are receiving offers, there is something seriously wrong with the company's intern selection process.
Do you have some sort of source for that figure? Every company I've worked at, including both Google and obscure outfits you've never heard of, has made an offer to far more than 1-5% of its interns. This random Quora answer says 70% at Google get offers, which seems high to me, but less off than 5%.
Most of them are worthless; of any given intern class at a first tier technology company (e.g., Apple), only ~1-5% will actually be offered a full time job.
I really doubt this number. Rehire rates are an important consideration for college students, and they talk. An offer rate below 50% would be damaging.
That said, a lot of people find better offers elsewhere, but no tech company is going to no-offer 90% of its interns and keep its reputation intact.
Those 1% are worth every penny, but you simply don't know who they are until you give the entire intern class the opportunity to demonstrate their abilities.