You can get a Pidgey or a Spearow relatively early on in your journey, which means by the time you run into a Doduo you'll already have a fairly strong flying type that you've journeyed with and have no reason to pick a new one up. That and with access to Mega Pidgeot and Starraptor, to most people there seems to be almost no reason to pick up a Dodrio. If you don't however, you'll be missing out on one of the oddest, yet most formidable normal/flying types in the game.
Let's check out this road runner's stats.
Dodrio has high attack and high speed with a plethora of moves at its disposal, which allows it to use them to their maximum effectiveness. It outspeeds many Pokémon and can shatter through some of the toughest of walls, as long as they don't have a resistance to normal or flying type moves. This is where Dodrio falls short, because as soon as it strikes it's a sitting duck for any other move that can be thrown at it, and with its abysmal defenses and HP, it'll fall in battle quickly. This is why the main mode of attack for Dodrio is to go all in and make sure there are no entry hazards waiting for it on the other side.
Image Source: Here