I agree with this in general. There are pros and cons to being a high performer and "wearer of many hats" (even better moreso if any of those hats are an essential part of operations). One pro is that you are less expendable and seen as more of a value to an organization. A con is the likelihood of getting pigeonholed into something you can't grow out of, or the company has no one else qualified to do.

Just as much as you should dress for the job you want, also don't dress for the job you don't want...meaning don't be so good at something you don't love or want to do, but are also coincidentally proficient at. That's an easy way to get stuck in a position and hit that career plateau that is ever so soul-sucking.

But on the other hand, the "jack of all" is also usually of the last lot to go on the chopping block and is seen more as an asset to overall operations-continuity.

I've weathered a few mass downsizings in my career beginning with the dot com crash and they are never fun. So I guess my advice to add is also be available and assertive to try out different roles and responsibilities, starting with what makes your boss happy and look good. I've gone from a one of several technical writers to having 3 different business cards for the same company to represent the various roles I performed. It wasn't what I signed up for, but I lasted through a lot of downturn until I left that company after 11 yrs. Anyway, tmi probably.