The question shouldn't be "why does web development require the use of garbage collection" but "why would you not use a language with a GC when you have the opportunity". Before Rust (and after the 90s or whenever hardware became sufficiently cheap) it would've been very odd to consider a non-GCed language for something like webdev. Even for things like high-frequency trading where reliable low latency is very important, some companies think using GCed languages like Java and inventing hacks to avoid GC pauses when necessary is a worthwhile tradeoff because of the productivity gain from having a GC.

Certainly Rust has done lots of cool stuff to make living without a GC easier. And maybe it has sufficient compensating advantages to make it worth using for things like webdev (although I wish more of its proponents would try different statically typed functional languages that share some of those advantages but don't make you manage memory manually). But lacking a GC is still pretty clearly a disadvantage outside of a few areas (namely, those where people often use C++).

> Web development without garbage collector sounds like a bad idea.

Before rust, all the mainstream non-gc'ed languages (i.e C/C++) were not recommended mainly due to potential security issues.

The only options left were gc'ed languages (e.g Python, Java, Go).

Now Rust enters which addresses a lot C/C++ issues but the ergonomics, lack of tooling & learning curve is too much for lot of basic web services.

For large scale web services, investing in Rust makes sense to make it more performant & resource efficient, especially a lot of $$ is riding on it.