This is not at all true. The needs of Servo have had a huge impact on the development of the Rust language. The Rust team prioritizes feedback from Rust users, the largest of which (larger than rustc itself) is currently Servo.

I believe what hobofan is implying is that the Rust developers have resisted bending the language solely to the needs of Servo, despite there originally being almost a 50/50 overlap between the Rust and Servo developers (nowadays the division is more clear, with pcwalton working full-time on Servo and brson working full-time on Rust).

The most notable example is the proposal variously known as "virtual structs" or "inheritance", which had a brief prototype implementation in Rust (circa 2013) solely to support Servo's needs (specifically regarding representing the DOM), but which met a wall of opposition from the community. Such a feature is still likely to appear sometime in the future (after all, if Servo needs it, then it's likely that others do too), but the Rust developers are taking their time to explore solutions that integrate the most cleanly with the rest of the language.

It is true in some sense, we don't just implement things Servo wants. If Rust was beholden to Servo, we would have put inheritance in the language over a year ago, for example. That said, the eventual work for "something inheritance like" is absolutely predicated on Servo's needs. But we put it on the roadmap and weight it like anything else.

That said, we do take their needs into account rather highly, just like any project with a large upstream user.

Just like we wouldn't want Rust to be useful for only compilers, "only compilers and web rendering engines" isn't much better.