An FM tuner is superfluous these days. FM always was a challenged technology and at current bitrates of the better internet radio stations, the imperfections of internet radio are far smaller than those of FM. In addition, you have a far wider choice, of course. A Chromecast Audio is an easy way to do this.
On the other hand, a receiver is hardly more expensive than just an integrated amplifier. It does not require a more expensive case, and it does not require a more expensive power supply, the two most expensive components. My guess would be that the extra component cost is only a few dollars. In the case of the Yamaha receivers, their advantage over and above their amplifiers is that the more expensive ones have more digital inputs - you quite quickly need more of those (at least three for a streamer like the Chromecast Audio, for the 2 channel output of the TV, and for the digital output of the disc player).
On the other hand, a receiver is hardly more expensive than just an integrated amplifier. It does not require a more expensive case, and it does not require a more expensive power supply, the two most expensive components. My guess would be that the extra component cost is only a few dollars. In the case of the Yamaha receivers, their advantage over and above their amplifiers is that the more expensive ones have more digital inputs - you quite quickly need more of those (at least three for a streamer like the Chromecast Audio, for the 2 channel output of the TV, and for the digital output of the disc player).