I’m a little late with my comments but just had to brag about my younger days with Heathkits and other companies! I learned how to solder the hard way (without any instructions) and put together a B/W TV, a color TV, an AM/FM receiver and various other little projects. I understand Heathkit is coming back and encourage you younger people to enjoy the hobby of putting together their kits after doing these soldering lessons.
Not everyone has soldering paste handy unless they are going to do a lot of soldering.
They are not as easy to use especially for beginners.