Everybody likes the game to go faster. So cards get made that do that. They get called engine cards. The one you've just suggested could be called that too.
(
https://xkcd.com/927)
Engines are meant to be helpful, in being what you want to build your deck around. If you want to grab a handful of
cards and have them be your deck, that's fine, but it's probably not going to do much. The game started as play-1-draw-1, and that strategy doesn't move beyond that. Now imagine that you select
Finest Crew of the Fleet, or
Here by Invitation, or
Home Away From Home, and now you've got a ready-made way to have a bunch of cards that do things together, and ease of play and/or rewards for doing things.
And as for why some engines have restrictions (which I think you've mentioned in other posts) -- that's because some players have been thinking more deviously than you (or me), and tried fusing
this powerful engine with
that powerful other card -- so Design made the restrictions so the engine on its own would make a decktype that's powerful and/or fun, without making a situation of a combo that's
too powerful.