You can also read advice saying that a glass of water before a meal is ideal for those trying to lose weight as it fills you before you start eating.
Personally, the google advice seems to be based on very faulty science. Water passes through the body or is absorbed quite quickly and will certainly not swill around in the stomach diluting the digestive juices. The chemicals in the digestion process are, anyway extremely corrosive, and a bit of dilution will make little difference.
Even if it is true wh would diluting the digestive juices be a bad thing? If the digestion process is slowed down, digesting our meals will take longer, we will feel fuller longer so will not be tempted to eating again too soon or snacking and grazing. What's not to like.