It suggests that:

you are a lazy piece of shit

you were incarcerated for bank robbery

you were on the run from the Feds living in Argentina

you went to Pakistan to attend a Jihadist training course (BTEC-diploma)

you were kidnapped by aliens and given daily anal probes (that never impresses the interviewers)

you were being trained in cutting-edge industrial espionage techniques by a rival company of the interviewer

you spent the time going through sex-reassignment procedures and changed your name to Gladys

you worked for the NSA

The average interviewer will think all of the above and more in the space of two milliseconds, whether any of these delusional thoughts have any basis in reality.

There is no logic in it. Holes are bad because holes are bad. I'm sure I can make up a reason for you, but IMO, its better to cut out the bullshit and just tell it to you straight.

Holes in a resume are bad because most people who look at resumes think that holes are a bad thing. Its simply the bias that exists in most jobs (that I've come across... anyway)