I've run all of my hobby projects, including personal web pages, a Wordpress site that serves a local club, a small single-JS web app, and E-mail hosting for my family and a few other domains, on a single $5/mo VPS, and have never received a bill higher than $5 for the past, I don't know... 15 years.
If your web site makes you money in proportion to the amount of views or bandwidth you use, by all means, go with a provider that increases your costs when your traffic rises. But if your web site does not make you money, why not host it somewhere for a flat rate?
I don't get that either. I earn all my money from my websites and serve > 1mio requests daily all from a single Vultr instance for less than $150 including backups and more traffic than I ever need. With monitoring, CDN, DNS, ddos protection, and whatever I pay about $200 a month, no surprised and a lot of room to grow or get HN hugged, or whatever.
I've been on a $25 instance for years for all my sites, which worked as well.
If your web site makes you money in proportion to the amount of views or bandwidth you use, by all means, go with a provider that increases your costs when your traffic rises. But if your web site does not make you money, why not host it somewhere for a flat rate?