Nowadays, there is an active discussion about why one should delete the "Thank you!" slide (and how to end appropriately his/her presentation). See, for instance,
I have failed to find any French articles regarding this issue.
Obviously, one would thank his audience. The trend that I see outside France is to make this orally rather than include an additional slide. E.g. the last slide could include some concluding remarks and perspectives. Once finished, one could say thank you for your attention without including an extra slide with some fancy layout repeating the oral idea.
So my question is rather simple: Is it still considered necessary for French presentation customs to include a "Merci de votre attention" slide (diapo)? Is it considered impolite its lack?