It is, in my opinion. This post: How to get Lirem 5 kernel log in /var/log/syslog in addition to systemd journal? - #4 by irvinewade tells you how to limit the size automatically.
Purism may have thought that for a relatively new phone it is better to have too much in the journal than too little, for when something needs troubleshooting - and that is certainly a logical decision - but my journal eventually became so slow to interrogate that it became counterproductive.