Never have I ever been the person with highest "overall activity, number of issues closed, merge requests completed, etc.", yet I have not been laid off in a very long time.
Last time I thought I was getting laid off, I misread the manager's comments as PIP.
How else would you measure how much work someone does, other than by how much tracked work that's attributed to them there is?
The people using these indicators probably don't care about someone who might have fewer closed issues but instead is helping out 5 people work more efficiently, but rather about people who are constantly shipping measurably less than others, stack ranking and all - in their minds, development should be viewed as some widget factory.
Just look at what happened to agile and how SAFE ended up: https://www.atlassian.com/agile/agile-at-scale
That's also how you get attempts to turn some abstract complexity evaluation (story points) into hours that could be billed to a client ahead of time, even though it probably shouldn't and doesn't work like that.