However, if you're looking to do strikes grimoire, there's some tips you can do to speed it up. This is a quote from the best [url=https://www.bungie.net/en/Forum/Post/101097919/0/0]Grimoire guide[/url] there is [quote]Need Strikes? [spoiler]Nightfall, Weeklies, and playlists don't count towards your strike completions. The only strikes that count are the original strikes on the planets. If you go into a strike by yourself, it will only count as one. However, I completed them with one person in my fire team, and it counted as THREE every time! Find a buddy and get them done![/spoiler] [/quote]

I'm not sure if its intentional or not. It's just the way strike grimoire has always been.