This is really just a way of mimicking what an anti-detect browser without the advanced options. I like the ingenuity and it will definitely work because Reddit won't link your accounts together (they do this with cookies) and you'll be using a different IP every time which adds another layer of protection. I totally understand why you would use this method and I think it's a great method for people who are managing multiple Reddit accounts in low-income countries or are just starting off and don't want to spend money on proxies and anti-detect browsers.
If you can afford it, I'd 100% still recommend an anti-detect browser. It makes your life so much easier and is more secure. You don't have to login to the account every time and cookies, cache, proxies, user agent, fingerprinting etc. are all managed automatically...
That being said I love the ingenuity and in all fairness using an incognito browser wasn't something that we even thought of when we were designing our systems...
Something else that you can look into when trying to rotate your IP addresses is the new iCloud Private Relay feature. You get it as an option with iCloud+, which costs 1 USD per month. If you're using a Mac and you use the Safari browser, your IP address when using Safari is rotated and it hides your home IP address. A lot of people don't know about this feature, and I'm assuming a lot of people don't have a Mac or don't want to pay the $1/month price, but it basically mimics a rotating residential proxy with high-quality IP addresses. You can even choose whether the IP rotates in your city or in your country. We've never tried to use this on a large scale, but when I did small-scale testing, it seemed to work really well.