It's just fake humility. The same people would get offended if you actually suggested they were lazy and incompetent.
Incompetence, I agree, sounds either self-deprecating or fake.
For most of my coding work I take it a step further than this with the simple premise that the code you wrote professionally is not for you. It’s for whoever next has to work on it, no matter their level of expertise. Sure, maybe you ‘just know’ that the equality operator comes between bitwise-OR and logical-OR in precedence, but the code isn’t for you so maybe just use the brackets anyway.
Being lazy and incompetent however is always fluctuating. There are days I'm lazy, there are days when I can work 12 hours and feel energized. There is also days where everything in my mind aligns and all the problems melt away. There is also days where I ram my head into the wall on some relatively simple problem.
The point being is that programming is something that no human can do without errors. So you want a language that provides as much low overhead guard rails as possible to stop yourself from shooting yourself in the foot. Even on the days you're lazy and incompetent.
That's how I see the statement they make.
Maybe, because it is all relative.
I know my flaws and compared to my (often unrealistically) high standards, I feel incompetent quite a lot. So I can say the above and mean it.
But if I get criticized as incompetent by someone way below my level, then yes, I might take offense and depending on the mood, also hit back (or ignore it).