The highest level of cringe you can feel is when you see people you know well in real life post on LinkedIn. The contrast between the way they speak in real life and on LinkedIn is often immense, you don't feel that level of contrast with random internet strangers.
On the other hand, people have commented (in real life to me) that my linkedin comments are bold, hilarious and entirely unprofessional- earning me a sort of credibility in their eyes for being authentic and having integrity.
(and probably more privately, they believe I am too outspoken..)
Pro’s/Con’s; just like with all public broadcast information.
Also, its always embarrassing when someone talks about a linkedin comment I have made, not because I am ashamed but because I am sort of used to a semi-anonymous shouting into the void style forum like hackernews.
Reminds me of a blog post I once read from a manager writing about all the qualities of being a good manager. I read it nodding along that they all seemed like good traits. Then in the comment section there was a post from someone saying something like "You were my manager at one point and honestly you were one of the worst managers I've had in my career. I didn't see many of these behaviours from you". The author responded with something like "I don't disagree. There's sometimes a gap between knowing and doing"
In my professional network, people mostly just reshare and like things their peers are doing or that they want to boost engagement for (mainly job postings, which they also post occasionally).
I _do_ have acquaintances I made outside of working life on LinkedIn, though - the only two that are really active are a mechanical engineer who mostly just posts about robotics and someone in marketing. I don't know if it's because I'm just really good friends with the latter person, but I've never felt annoyed reading their posts; they mostly seem to just talk about enjoying conferences or new externally facing projects - ad campaigns, large-scale promotions, etc - wherever they are currently working. I don't know if part of that is they're in the EU and the culture for marketers there is different?
I have a friend who behaves similarly on linkedin and in real life, and he's very blunt. I like how he calls out some crap on linkedin posts, and nobody dares to like his comments, even though I'm sure everybody approves.
Overall, I don't see anyone I know being a cringe bootlicker on LinkedIn. These people are very visible, but probably a small minority of users.