TF2 faces a lot of difficulty in its success, but the comparison to smash is justified. While it's difficult to view (not necessarily compared to mobas, but something like CS is incredibly intuitive), matchmaking should help with this, if it makes people's ingame experience more representative of a competitive stream. TF2, like melee features a lot of fast paced mechanical skill, and unlike almost any other game with quake style dm, it's not a quake clone, having its own unique classes and gamemodes.
Like smash, the concept of comp in TF2 has been for the most part ignored by devs for years, with many default features in the normal game that have to be turned off/aren't used in comp (as many characters/stages in smash aren't used, and items are off altogether). Nintendo even added anti-competitive features such as random tripping in brawl. Despite this complexity and random stuff in the games that detracts from them being taken seriously competitively when compared to other games in their respective genres, the core mechanics in both TF2 and smash still make the potential for skilled play very high.
Both games are extremely well known casually, and both have well known and respected developers who have the potential to back competitive strongly. Both are relatively old games that are still popular.
Moving away from the smash analogy, TF2 also has mechanics like pushing off advantages, turning small advantages into larger ones as well as capitalizing off of mistakes which creates a good flow to the game. This provides a balance between action and stalemates which makes casting easier and watching more entertaining. The game at a competitive level also often has better production value than many top level esports which is something to note.
I really feel that TF2 has all the ingredients there for a successful competitive game, although it's probably unrealistic to expect it to be on the level of even smash, but the only thing that will grow it at this stage is support from valve and general interest in the game. The community has gone above and beyond to help grow the game as much as it can, but without the money or the playerbase, the game won't see anything exponential.