One "+" less than max is "tanking" the stat?... Who is being silly/intellectually dishonest? The "enhance ability" doesnt even give you a "+" to those stats like the spells of old, just some bonuses to checks/saves regarding those stats... in case you missed that and weren't being intellectually dishonest... again... ;D
I didnt check but will also assume that item that is "similar" to the +10 item(effectively just that if a player has a use for the stat and wants it to be... its not silly or anything else... just numbers... that also equate to 20+ build points like i said) doesnt provide near the benefit this one does but you didn't say what that item was... I think i know why...
I previously didnt insult you directly or otherwise... grow some thicker skin or probably get off the internets... ;D
Also, while i can admit i dont know it all, my knowledge of 5ed isnt as bad as you would like to believe, i just haven't had the chance to see a good deal of it in live action and at higher levels yet... i feel i can mostly stand by what i said... even the 2nd level stat boosting spells, as they in fact no longer provide actual pluses to the stats... another pretty in your face indicator this particular item is a Larian computer programmer type brainchild... not WotC imho...
One item... not a game breaker... just one little tid bit during a game that makes you wonder if the DM knows what they are doing... certainly a smaller issue than things like jump/disengage...

Peace... Llev...