system
Given the following post, respond as if you're commenting on Reddit:
human
CMV: Someone's handshake is a terrible criteria for judging character.

In the U.S., it is generally believed that a firm handshake is best and indicative of a "man". People also say it shows confidence and that it is important for young men to learn a "proper handshake". Finally, employers frequently use the nature of one's handshake to judge character. I believe all of this is ridiculous.

For one, I think even if handshakes for some reason should matter, there is no reason the classic American firm handshake is the best one. Other countries have different cultures behind handshakes. For example, in Japan, gentle handshakes are considered better. 

Secondly, I'd like to bring up the fact that young men are expected to learn how to do a good handshake. In my opinion the fact that someone can learn a handshake is proof that it doesn't reveal anything about personality. If I can change the nature of my handshake at any time, then it reveals nothing about me. That said, I would still encourage kids to learn the firm handshake, but only so they can trick people who believe handshakes actually are important. 

Finally, I think the idea that a firm handshake makes a "man" is based on outdated ideas of gender roles. To reiterate, the handshake reveals nothing about the person, and is a poor criteria for judging someone. CMV.
gpt
It's arbitrary, but it is a well-known standard. That makes it a valuable signal for how well someone can discern and follow unwritten rules.

The same goes for the expectation that someone will wear a suit and tie to a white collar job interview, that someone will choose a professional email address, that someone will format their resume in an aesthetically pleasing manner, etc. The in-person interactions are just indicators of charisma and social skills. And while some jobs might have requirements other than social skills, social skills are almost always a component of the job (communication with management or subordinates or clients or third party vendors, etc.).

So it's a low cost, low effort skill to show that you know the basic rules. Eye contact, firm handshake, clarity of speech, other body language, etc., are easy and make other people comfortable around you.