The lts kernel in Arch is aimed at server use, with several config options set so that it is optimized for servers (with CONFIG_PREEMPT being the one that was most discussed here on the forum). It is not intended by its maintainer to be used as main desktop kernel.
Yes, it is recommended to have it installed as fallback kernel in case the regular linux/linux-zen kernels have issues, but it is not optimal to use it as default kernel on every machine.
Edit:
https://www.reddit.com/r/archlinux/comments/md4j2w/the_linuxlts_kernel_not_fit_for_desktop_use/