The way you chose to phrase your question implies a Mac can passively become affected by malicious software, and that does not happen. Therefore the answer to your question as written is no, Macs do not "get" malware.
However, plenty of deliberately malicious, ill-conceived or just poorly written software exists, ready to be installed on your Mac — if you explicitly allow it to be installed. There is nothing new about that. A Mac would not be the useful tool that it is without that ability.
Most likely, those who develop and disseminate products that "Malwarebytes" is designed to remove don't consider their products malware. They serve a purpose for their developers in the exact same manner that "Malwarebytes" does for its developers. I doubt they consider it malware either. I doubt MacPaw considers their "CleanMyMac" product malware, but countless people on this site affected by it and similar products disagree.
The point is that nothing gets installed on a Mac without your consent. But if you are motivated to install something malicious, you may certainly do so.