It's because of the warmth these bulbs provide when dimming. Most LEDs dim on compatible dimmers, but they tend to retain their initial color temperature. For instance, if the LED started at around 2700K (similar to an incandescent bulb), it would stay at about 2700K as it dimmed.
But incandescent bulbs become even warmer as they dim, approaching 2200K in color. If you have dimmers in your home, you're probably familiar with the warm, orange glow this creates. Philips new "Real Bulbs" mimic that increasing warmth when dimming. So if you're looking for the most accurate incandescent replacement in LED bulbs today, you can't beat this affordable option!