While you can play that way, combinations are usually the essence of Race for the Galaxy.
The ones in the basic set are pretty much laid out for you, since the cards involved often mention each other by name. A typical consumption engine centers around 3 blue production worlds, Consumer Markets, and Free Trade Association. Free Trade Association gives you 1 point + 1 card for up to 3 blue goods, and Consumer Markets gives you an extra card for every blue good you produce, plus some extra Blue consumption if you end up with more than 3 blue worlds. Free Trade Association gains points just for having Consumer Market on the table, as well as some specific blue worlds (i.e. Expanding Colony), just to underline how it’s supposed to be played.
Another obvious combination is the mining-related cards, Mining Robots, Mining Conglomerate, and Mining League. Again, Mining League mentions the other related cards by name. It’s an obvious strategy for Alpha Centauri since you get -1 cost to brown worlds. Get Mining Robots out early, and most brown worlds will be free or nearly free. Even the overpriced New Earth isn’t so bad at cost 3.
Some combinations aren’t about produce / consume, but about laying down high-value worlds. Alien Tech Institute + Alien Rosetta Stone makes most Alien worlds quite cheap, and can get you alien military worlds with little or no military.
There are other, less obvious but powerful combinations. Colony Ship is often iffy by itself, but can give high-scoring military worlds with Contact Specialist, without the long build up of a military strategy.
As you add more expansions, some of the combinations in the basic set are greatly diluted because specific, named cards are harder to get, but others open up. For example, Research Labs gains you +1 card from each Alien (yellow) good you produce. Producing yellow goods is pretty rare in the basic game, but much more common with the expansions with Damaged Alien Factory and Alien Toy Shop.
The expansions of course also have combination that center around cards that aren’t in the basic set at all. Uplift Code comes to mind. Prior to Uplift Code, there are some genes-related developments like Galactic League and Galactic Genome Project, but nothing as powerful as the Consumer Markets or Diversified Economy.