Nonsense! There are several plugins for the use of webp in Wordpress like https://wordpress.org/plugins/webp-express/
Seems like there are always people looking for arguments against good ideas for future development of Affinity like webp. We are using webp in every website we create including Wordpress for years now. All major browsers can work with webp except for Safari therefore we use a jpg fallback.
Only for Google & Co and SEO reasons you are a fool when you don't implement it in your website.
Example: A cross browser background image (unfortunately not possible to create in Affinity Photo without the use of a webp converter):
<picture>
<source media="(max-width: 475px) and (orientation: portrait)"
type="image/webp"
data-sizes="auto"
srcset="data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=="
data-srcset="
Responsive-Images/Home/back-home/bg-Phone-webp/home-back-phone_vsimc2_c_scale%2Cw_480.webp 480w,
Responsive-Images/Home/back-home/bg-Phone-webp/home-back-phone_vsimc2_c_scale%2Cw_905.webp 905w,
Responsive-Images/Home/back-home/bg-Phone-webp/home-back-phone_vsimc2_c_scale%2Cw_1200.webp 1200w" class="lazyload">
<source media="(max-width: 475px) and (orientation: portrait)"
data-sizes="auto"
srcset="data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=="
data-srcset="
Responsive-Images/Home/back-home/bg-Phone-jpg/home-back-phone_vsimc2_c_scale%2Cw_480.jpg 480w,
Responsive-Images/Home/back-home/bg-Phone-jpg/home-back-phone_vsimc2_c_scale%2Cw_905.jpg 905w,
Responsive-Images/Home/back-home/bg-Phone-jpg/home-back-phone_vsimc2_c_scale%2Cw_1200.jpg 1200w" class="lazyload">
<source
media="(min-width: 476px) and (orientation: portrait)"
type="image/webp"
data-sizes="auto"
srcset="data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=="
data-srcset="
Responsive-Images/Home/back-home/bg-Tablets-webp/home-back-tablet_asvcpy_c_scale%2Cw_768.webp 768w,
Responsive-Images/Home/back-home/bg-Tablets-webp/home-back-tablet_asvcpy_c_scale%2Cw_1213.webp 1213w,
Responsive-Images/Home/back-home/bg-Tablets-webp/home-back-tablet_asvcpy_c_scale%2Cw_1536.webp 1536w" class="lazyload">
<source
media="(min-width: 476px) and (orientation: portrait)"
data-sizes="auto"
srcset="data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=="
data-srcset="
Responsive-Images/Home/back-home/bg-Tablets-jpg/home-back-tablet_asvcpy_c_scale%2Cw_768.jpg 768w,
Responsive-Images/Home/back-home/bg-Tablets-jpg/home-back-tablet_asvcpy_c_scale%2Cw_1213.jpg 1213w,
Responsive-Images/Home/back-home/bg-Tablets-jpg/home-back-tablet_asvcpy_c_scale%2Cw_1536.jpg 1536w" class="lazyload">
<source media="(max-width: 4800px)"
type="image/webp"
data-sizes="auto"
srcset="data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=="
data-srcset="
Responsive-Images/Home/back-home/bg-wide-webp/home-back-wide_q1epvc_c_scale%2Cw_500.webp 500w,
Responsive-Images/Home/back-home/bg-wide-webp/home-back-wide_q1epvc_c_scale%2Cw_1656.webp 1656w,
Responsive-Images/Home/back-home/bg-wide-webp/home-back-wide_q1epvc_c_scale%2Cw_2400.webp 2400w,
Responsive-Images/Home/back-home/bg-wide-webp/home-back-wide_q1epvc_c_scale%2Cw_3007.webp 3007w,
Responsive-Images/Home/back-home/bg-wide-webp/home-back-wide_q1epvc_c_scale%2Cw_3516.webp 3516w,
Responsive-Images/Home/back-home/bg-wide-webp/home-back-wide_q1epvc_c_scale%2Cw_3840.webp 3840w" class="lazyload">
<img data-sizes="auto"
srcset="data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=="
data-srcset="
Responsive-Images/Home/back-home/bg-wide-jpg/home-back-wide_q1epvc_c_scale%2Cw_500.jpg 500w,
Responsive-Images/Home/back-home/bg-wide-jpg/home-back-wide_q1epvc_c_scale%2Cw_1656.jpg 1656w,
Responsive-Images/Home/back-home/bg-wide-jpg/home-back-wide_q1epvc_c_scale%2Cw_2400.jpg 2400w,
Responsive-Images/Home/back-home/bg-wide-jpg/home-back-wide_q1epvc_c_scale%2Cw_3007.jpg 3007w,
Responsive-Images/Home/back-home/bg-wide-jpg/home-back-wide_q1epvc_c_scale%2Cw_3516.jpg 3516w,
Responsive-Images/Home/back-home/bg-wide-jpg/home-back-wide_q1epvc_c_scale%2Cw_3840.jpg 3840w" class="lazyload"
src="data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==" alt="Full Screen achtergrondfoto met woonamer, daarin een bankstel met Wil Art kussens en schilderijen aan de muur">
</picture>