Why do people call/re-raise preflop?

[Abbaddabba]

There are a lot of really bad poker players out there.

Limp-raising, relative to many things they do, is fairly insignificant.

It's not good, but it's not terrible.

When you see people do this though, you can usually narrow their range of hands down. Especially if it's NL. If it's limit, people become erratic with strange things.

There is a time and a place for it, mind you. For example, if the table is loose, which justifies you open limping with a variety of hands including lowish suited broadways to low to mid pocket pairs (say, 7's or JQs)... if (for one reason or another) it gets folded ot the blinds and one of the blinds raises, you can justify 3betting.