1. Spam filter behavior has changed because spam has increased in volume and sophistication, not because ISPs want to save money, or to eliminate competition. Some techniques that worked well 5 years ago aren't as effective anymore. One of the consequences of this has been a reduction in the value of IP reputation, from a spam signal perspective, particularly for low-volume IPs.
2. IP range reputation does matter. The increase in the value of IP range reputation, as a spam signal, has paralleled the decline in value of low-volume IP reputation. In practice, this means you need to either send enough volume to outweigh the reputation of your IP range (exact quantity varies based on a lot of variables, but as a very rough approximation, 1000 messages a day), or find an IP range with good reputation.
IP range reputation is not easy to assess, sometimes even for email professionals. So you can either gamble with a residential ISP IP, or a VPS IP, or you can find a provider that spends time, effort, and expertise on managing IP range reputation. The practical solution for most senders is the latter. Many of these offer a free tier, and many options are available among providers of all sizes.
3. The filtering behavior reported here is either misunderstood or misrepresented. First, no, no major ISP (Gmail, Yahoo, Microsoft/Outlook, icloud) is going to permanently block an IP range; filters are designed to be dynamic. In severe, ongoing, high-volume spam scenarios, you could see a 2-week block, maybe occasionally 30 days. But never "one strike".
Mail deletion without a bounce also cam happen, particularly at Microsoft, but again it's almost never seen for legitimate mail - that response is reserved for long-term, severe spam scenarios, where anyone reasonable would agree that a block is warranted. And, again, this is dynamic.
So it looks like OP is either exaggerating, or has been trying to send from IP ranges with unusually bad spam problems.