1. Older companies tend to have wider footprint of real world use in various contexts thereby having a wider "body of work" for objective analysis and review.
2. There is switching cost when you get the 'thank you from the incredible journey" email or blogpost. So it is important to have companies that are self-sufficient and aren't at the risk of being acquired and shutdown which new companies are much more prone to.
PS: It is acknowledged that new companies most likely have fresher takes on old problems but you should also cater for their negatives enumerated above.
There's definitely value and opportunity that can be found in using the newest tech from the freshest companies. You can often find great value from their pricing, better UI, improved results, etc.
So my comment was in no way meant to bash using a startup. It was meant more to point out that there's a double-edged sword here by focusing on startups as there are real risks and trade-offs.
They also seem like they might have more proven business models, which is important when you're relying on it for a core function of your business. The last thing you want is some fresh startup that craters and forces you to scramble to find and implement a replacement when they fail to close their next funding round and need to shutter things.