Better than not even starting, and not as bad as you’d think.
You aren’t always starting from scratch, and even if you were, it’s not exactly a bad place to be. Your experiences to date can by no means be completely discounted. Plus, coming in with a beginner’s mind can often lead to insights that more seasoned professionals have either overlooked, or simply didn’t realise.
Starting from scratch is an opportunity to try something new. It’s a chance to see things from a different perspective, and to bring a different perspective to the way things are done.
That in itself is as worthy a reason of anything of starting, even from scratch.