yup - for one gallon kits, it's what the instructions state and it appears to be the "simplest thing possible" that works.
One gallon batches can be a good size for people who want to brew, but live in a small space. It's also a good size for people who like a lot of variety.
The smaller volumes of 1, 1.7, 2.5 or 3.0 gallon batches can also have appeal to people who can't (or don't want to) deal with the weight of 5 or 10 gallons of wort.
And then, there was a post over on reddit earlier this month, where the poster stated they were brewing a quick one gallon batch while mashing for their 5 gallon batch.
There are many, many ways to brew it well.