Learn English – What’s the difference between “the lack” and “the lacking”

In casual usage, perk works well, in the sense they were an added benefit.However whether they were useful per se, is not clear. They could merely have been stress busters or fun.

'informative and fun' is something I can think of.

Hope it helps.

That person is "out of their depth", but you are "at a loss".

Both from the free dictionary:

be out of your depth - to not have the knowledge, experience, or skills to deal with a particular subject or situation; When Ruth started talking about the differences between the databases, I knew I was out of my depth. By half-time, England was losing 4-0 and the English players were looking hopelessly out of their depth.

Adj. 1. at a loss - filled with bewilderment; "at a loss to understand those remarks"; "puzzled that she left without saying goodbye"

In a less formal setting, you might instead say that they were talking out of their ass, rendering you speechless.

From the Urban Dictionary:

talking out of your ass To make an obviously false claim. To attempt discussion on a topic with no prior knowledge of it usually results in this. The moon landing was a hoax? You're talking out of your ass.

or

When someone says something stupid that they have no proof of. For example, "The Space Shuttle was destroyed by TERRORISTS!"

From the Free Dictionary:

speech·less (spēch′lĭs) adj. 2. Temporarily unable to speak, as through astonishment.