I have a mid-sized website with about 60K visitors a month. I've tried various free tools. But the one I come back to again and again is Google Search Console (GSC). Most of my traffic is organic Google search results. GSC gives me extensive and detailed knowledge about traffic to my 500+ articles. I spend some time on GSC almost every workday.
Almost entire Net uses the free tools, starting from the operating systems (with the HTTP servers), through the programming languages, and to the content management systems. So far, everything works.
No, rather opposite, the paid services limit their usage according to the money, which you pay for them, while the genuinely free tools, which have no paid versions, usually have only the technical limits, which ensure, that every visitor may use these genuinely free tools without the interference from the other visitors.
My SEO tools — After nearly 20 years of operating my nonprofit website, I've pretty much abandoned Google Analytics in favor of the simpler but still quite helpful StatCounter (it has a small monthly fee). With that and the extremely SEO-helpful, free Google Search Console, I'm getting enough data to keep my one-man-office website at 50K-60K visitors a month. Frankly, I got tired of chasing every new SEO trend across multiple tools. It was taking all the fun out of doing a website. These days, by keeping it simple, working reasonable hours (for age 80), and being content with modest success, webmastering is fun again. On the other hand, I understand how those of you in the for-profit sector may not have the same stress-free environment that I have as a self-funded, "hobby" nonprofit with small costs (hosting, firewall, etc.).
Usually free tools have some technical limits, which ensure, that every visitor may use paid tools) Moreover , I believe that we have to support all developers and use free trial and then pay for using that brilliant tool
Yes, the different business models are useful for the different purposes. Usually, if you just use the free tool, then this usage is already beneficial for the author of this free tool.
If you are working on your own website, then I guess free SEO tools are fine. However, if you provide SEO services, you should acquire adequate SEO resources to provide optimum performance for clients.
A tool I thought was pretty good is Mangools, it's a fraction of the price of some of the other SEO software out there plus you get 10 days to have a play with it.