This doesn't happen with it written as 3K3. Saame system is usually used for capacitors also. Also, you may have noticed that some of my circuits are a litle tight. Imagine fighting such a drawing when you are trying to trace a wiring fault whilst balanced precariously on the top of a machine some 20 feet in the air. Dense drawings mean small paper and 3.3K is longer than 3K3.
Some capacitors use the same method of showing the value by colour code.
This is the series in the chart above. There exist also E24, E48 and E96 series. In electronics, particularly at the beginner's level, we start with certain postulates such as 'take a single transistor, and bias it from a 12v supply with 1mA collector current so that its collector sits at half the supply voltage'. So instead of ending up with, for instance, 6.1K we could start with 4K7 and work from that. But, as a manufacturer, everytime I introduce another item on to a parts list, that's another part for stores to count out, for production to insert, for inspection to inspect and for the testers to check.