Great questions—let’s break this down step by step, since these are common pain points for teams building live streaming workflows.

Live streaming has unique demands that make dedicated encoders (whether software or hardware) necessary, even with modern browser capabilities:

• Real-time performance & efficiency: Raw camera video is uncompressed—we’re talking gigabytes per minute. Encoders compress this into efficient formats like H.264/AV1 while keeping latency low. Browsers do have basic encoding via APIs like MediaRecorder, but they’re optimized for general use, not the consistent low-latency, high-quality output required for professional live streams.
• Format & compatibility control: Different streaming platforms (YouTube, Twitch, custom CDNs) require specific codecs, bitrate tiers, and container formats. Dedicated encoders let you fine-tune these settings to ensure your stream works across all devices and platforms—granular control that browser-native tools often don’t expose.
• Advanced feature support: Professional streams need things like multi-bitrate encoding (so slow-connection viewers get lower quality without buffering), overlays, noise reduction, and hardware acceleration. Most browser APIs don’t offer these out of the box, so building them yourself would mean heavy, hard-to-maintain custom code.
• Reliability for live scenarios: Live streams can’t afford crashes or glitches. Dedicated encoders are built to handle edge cases—like sudden network drops or camera disconnects—with fallback mechanisms that browser-based setups usually lack unless you build them from scratch.

First off: There’s no full "all-in-one" API that handles capture, encoding, and streaming end-to-end for professional use yet, but it’s not because of YouTube/Vimeo copyright restrictions. In fact, both platforms already support browser-based streaming (YouTube has a "Stream from browser" option, for example)—their copyright policies don’t block third-party tools from doing the same.

The real barriers are cost, scale, and technical complexity:

• Browser compatibility headaches: WebCodecs (the modern API for low-level video encoding in browsers) is still relatively new and not fully supported across all older browsers. Building an API that works consistently on Chrome, Firefox, Safari, and mobile devices requires massive engineering effort to handle edge cases and fallbacks.
• Server-side infrastructure costs: An all-in-one API would need to handle not just browser-side encoding, but also ingesting streams, transcoding for different devices, and distributing via CDNs. Transcoding at scale is expensive—each stream might need multiple bitrate versions, and serving to thousands of viewers requires robust CDN integration that’s costly to maintain.
• Commercial trade-offs: Most streaming services focus on either ingestion/encoding or player/distribution because building both is resource-intensive. The "closest" tools you found (embed players + stream output) are a middle ground—they let services focus on their core strength (distribution) while leaving encoding to specialized tools.
• Client device performance limits: Browser-based encoding relies on the user’s device CPU/GPU. For professional streams, this can be inconsistent—older devices might struggle to encode high-quality video without lag, which is a problem if you need reliable streams from any device.

That said, things are improving: WebCodecs is making browser-based professional encoding more feasible, and some smaller services are starting to offer tighter integration between browser capture and streaming. But for now, the split between encoding tools and streaming platforms is mostly a practical, cost-driven choice rather than a legal one.

内容的提问来源于stack exchange，提问作者N. J.