It doesn't really need to run anything "substantial" though. Running some janky wordpress site with some scabbed-on ecommerce customizations is like 50% of the internet.
a 1vCPU 512mb instance is plenty for most base cases. Maybe you need one additional machine to act as a background worker. I am sure there are some noisy neighbors but to say its underpowered is silly.
I'm calling it underpowered because the $5 one had trouble running my custom ssh daemon. ssh! the cryptography for that shouldn't chug down the server I'm renting from them. a bigger instance from them isn't having the same problems.
For $5 you get:
Latest gen CPUs and RAM
HTTPS
DDoS protection
Cloudflare CDN
Autoscale
Competent support
I'd say the best part is the predictable monthly prices
And while most people probably don't care, they are an established public company, so there is more chance they will exist in 10 years