Whether you build an antenna on your own, install a prebuilt antenna, or have someone else build it, grounding is a critical part of installation.
Offering advice to not ground outside antennas is irresponsible, contrary to all known laws of physics, civil law, and city codes pertaining to static charge buildup, and downright criminal!
There are three types of grounds. In order of difficulty to achieve, they are (from most difficult to least difficult):
Radio frequency (RF) grounding
The methods and practices used to achieve each of these are different. Static grounding is the most difficult to do with guaranteed results, while electrical grounding is easy and can be considered to work perfectly in most cases. RF and electrical grounding are not important for static discharge (lightning) safety, so I've left them out with regard to outdoor antennas.
The general rule on outside antennas is that they need to be grounded. There is literally no known government agency that recommends antennas not be grounded for safety. Indeed, many local and city codes require grounding.
The probability of direct and secondary static electricity (lightning) strikes increases with the buildup of static charge at points of conductivity, and of course the metal mast or pole of an outdoor antenna is perfect for doing just that. Static electricity is built up during a thunderstorm as wind blows over the metal structures. ...