So it is normal for us to encounter many assessments during an internship right? Then why don't firms just offer assessments since they mainly judge us on those assessments... Why do they want us to attend internships?
Not necessarily. You could have no assessments during a vacation scheme/internship.
Some firms do have assessments as part of their internships though. Mainly things like group exercises, in the forms of research tasks or client pitches.
Because assessment centres are simulations - they don’t really see you do the work in a real life environment. A vacation scheme allows you to see this on a more practical level, and over a longer period of time (which is probably much more reliable than a few hours).
Internships are also good in allowing the candidate to work out if that’s the firm they want to train at, so it’s very much a two way process, where firms can try and sel the benefits of why a intern should join them longer term.