Professionalism

There is quite a large amount of novels with disastrous beginnings. They often include a disclaimer that the story and grammer get better over time. This is then topped off with specific chapter references where they've gained an editor (usually at a relatively close point to the first chapter).

Although a bad story can somewhat be excused, as a rewrite usually isn't a realistic option, not fixing up grammer and other mistakes is inexcusable.

If even the first chapter is bad, there's a whole boatload of issues being hidden. It doesn't matter if the novel truly does improve (grammer-wise) latter down the line, as corners are obviously being cut.

If the author couldn't even bother to give a good first impression of their work, they aren't committed enough. (I don't care if they've written hundreds or thousands of chapters)

They're basically restricting their own potential to gain new readers.