Why do hiring managers frown at long resumes?

Often it's fluff I don't want to see. i'll lose interest. Be brief, factual and save the rest for the interview.

Effective communication should be short and to the point.

Because they have many to go through and long ones take more time to review.

Too much job hopping less career stability and success in each company.

They might be to busy or tired

Candidate is trying too hard. Business correspondence should be on point and concise

Because we need people who can net out the most important points. We typically have multiple people we're managing, and multiple projects, and there's not enough time in the day for pointless details.

Depends on the position the candidate is applying for as well as the format of the resume. But typically 2 pages max.

Most of the education or work experience is too much for the job in question. Also sometimes they are fake too. If you go get a job as a cashier would you need a phd? also if there is a long work experience is the person really reliable or do they just work for the love of working--then you surmise that maybe some of those degrees are not true.

Cause they don’t wanna work

We typically get a lot of resumes in response to a job advertisement, and we will first quickly create a shortlist of candidates, before further spending a bit more time reviewing the resume to narrowing down to those we will call for an interview. If we cannot quickly determine whether the candidate has the potential to meet our requirements then we either have to spend more time or more likely reject it and move on.

It looks like you bounce from job to job with no real commitment

It's the kitchen sink approach. It shows me that you didn't tailor your resume to show the qualities that you think may be pertinent/valuable to this role. Also, I want to use your resume as a highlight of talking points for our interview. By giving me a long resume I have to sift through a ton of information to find those talking points.

Time is limited.