Tapping into both my own uni graphics design and a past life as senior exec at a mega corp: because designers that use bad tools to make unusable presentations are failing "you had one job", to make something presentable across the variety of business modalities.

Being able to email the presentation and copy text from it are generally more important to communications impact and utility in the workplace than how it looks.

Being aware what your tool does to the presentation is part of the job you're learning in school.

Because they made a bad tool choice for their own convenience ? That leads here to big images and unselectable text, no accessibility.

same reason you'd downgrade a programming student if they handed in an assignment as an Excel macro? Not just because of the VBA but because to use it you now need to buy MS Office?