According to https://devdocs.magento.com/guides/v2.4/config-guide/cli/config-cli-subcommands-cron.html
"Several Magento features require at least one cron job, which schedules activities to occur in the future. A partial list of these activities follows"
That includes basics like sending transactional emails (Order Confirmations, Shipping Confirmations, etc.).
When it comes to shared hosting, I'd also caution that Magento 2 is considered a more resource-intensive than Magento 1, and more reliant on caching solutions. Additionally, new versions of M2 use Elasticsearch rather than native search, which you may not be able to install in your shared hosting environment either.
Magento 2, especially the latest versions, has not been specifically built with shared hosting in mind. It's not intended to compete with WordPress/WooCommerce. It's definitely a more mid-market product than a small business tool at this point.
Don't get me wrong, I'm a huge proponent of Magento, but from what you've shared, it definitely sounds like your needs and goals put you outside of the average user. You may want to stick with M2 because you love Magento, but you may need a more robust hosting environment.
On the flip side, if you want to stick with Magento 1, you should be sure to get patches from Mage-One or Openmage helping to elongate the life of your existing store. That plus other basics that a good Magento host will include, like a well-configured web application firewall (WAF), malware scanner, and intrusion detection system will help keep you safe and ideally PCI compliant for a long time to come.
Best of luck!
