There is a reason for this, CiG was not an established studio, they didn't have the financial backers to make the game first and then release a finished product for people to buy.
So the idea was for backers to fund the game as its being developed and it return have access to a playable version of the game as its being developed.
This is what's happened, for the devs to make playable versions of whatever progress they have made at fixed 3 month intervals probably creates its own challenges and time resources. Bugs included.
Ah, the old "they had to build a company first" line. I was wondering when this card would be played.
Indeed, you are correct, they did. There are just some problems with making this an excuse.
1) At launch they showed off a demo implying they had already done a lot of work. They said they had been working on it for a year already and it was kind of "look what we've already achieved!" There is even a statement from one of the first devs they actually started working on it in 2010.
2) CR's own statements they would have a release in 2-3 years "otherwise things will get stale". CR never said back then they had to build a company before they could release the game. They said, give us 5.5 million and we will create you the BDSSE in just a few years.
3) CIG from the start heavily relied on contractors. At one point they were contracting out to around 10 different companies while they built the company. Most of those are gone now, most notably Illfonic, but Turbulent remain and are becoming an even more important part of CIG's plans these days. So the romanticized vision of the first couple of years just being Chris and a few guys working on Star Citizen is just a fantasy.
4) Development methodology. I mentioned Agile to you before. The point of Agile is to focus on development in small parts and in each sprint produce a working deliverable. Now, with a project like Star Citizen, you don't get a working product from just a few sprints of course, but each component developed should work by itself. CIG could have followed Agile to develop a basic working game in a few years. Something like flying a spaceship around with a number of working gameplay loops, added some polish, and made a release of it, showing backers they could deliver on their promises. This could have been Star Citizen 1.0. At this point, they have a releasable product and go on to develop it further through the sale of DLCs. They only really needed kickstarter to get version 1.0 out of the door with some buffer to make version 2.0. CIG, for whatever reason, chose not to do this. Probably because they saw how much money people were giving them and simply thought they could do everything at once while continuing to expand the scope of the 1.0 release. They didn't have to make fully landable planets part of SC 1.0, they chose to do that themselves. They never asked backers to vote on it.
It was entirely CIG's decision to keep the game in eternal alpha, instead of delivering a 1.0 and freeing themselves from the need for eternal funding. But that would have required them to actually hold themselves responsible for delivering a product and iterating on it, risking failure and criticism.
As i've said before, CIG have taken 9 years and close to 500 million and they still haven't produced something that is on a par with what they said they could do in 2-3 years with 5.5 million.