No, not always, but often.
I see many scholars who know the Chazon Ish lacked important Achronim, but the fact means little to them (although far more conservative in their own respect). This is true with certain Rishonim, too, especially famously on Eruvin, see Rabbi Brand on Eruvin regarding a 17-Amah RHR .
For example, the Chazon Ish regarded using even a Chumash for Shnayim Mikra, unless there is no choice, as “דברים שבכתב אי אתה רשאי לאומרן על פה”, but many Achronim have proven the Gemara is lenient about this whole prohibition. By the way, this is why his students seem “illiterate” when quoting Pesukim during lectures!
(An example to prove the rule is the Chazon Ish quoting שו”ת פרי יצחק בלאזר to be lenient on lending without a shtar.)
The Chazon Ish lacked most Achronim and regretted missing out on at least some of them (like the Levush, according to “Ma’aseh Ish” somewhere), so he wouldn’t totally disagree with the famous Rabbi Yitzchak Kanpanton quote in Darkei Hatalmud: אין חכמת אדם מגעת אלא עד מקום שספריו מגיעים — brazenly used by sophomoric Rabbi Ovadya Yosef to minimize the halachic influence of the Chazon Ish. And he himself occasionally conditions his ruling on the words of the Achronim, unknown to him, such as the right age for marriage (Kiddushin 148 on Daf 29b, end), O.C. at the end of chapter 26 regarding Vayechulu, whether modern bathrooms resemble בתי כסאי דפרסאי (some recent Achronim are less unsure), and more, so it’s hard to see where that disclaimer would not apply (though not ללמד על הכלל כולו).
Not to mention the honest caveat: אם מבואר בראשונים הפכו (in spite of his concealing occasional disagreement with Rishonim by “re-explaining” them, etc.). But I must assume he means more than a simple reminder of Rema, Shulchan Aruch C.M. 25:2:
אם נמצא לפעמים תשובת גאון ולא עלה זכרונו על ספר, ונמצאו אחרים חולקים עליו, אין צריכים לפסוק כדברי האחרונים, שאפשר שלא ידעו דברי הגאון, ואי הוי שמיע להו הוי הדרי בהו!
Yes, the Chazon Ish could swiftly reinterpret new information in startling fashion, such as the famous essay against Rabbi Shimon Shkop’s comment on the Rema, taken by the hasty (see page 8 here) to demonstrate his supposed hashkafic bullheadedness. But so what?! (And he mercifully taught us all a tiny bit of how to do the same.)
I think this is also why the Chazon Ish seems to regard Jewish rationalism as heretical or close to that (in some cases); he was virtually unaware of the sheer diversity of opinion in Jewish tradition on these issues (and see this counter-argument).
Poverty means you can’t readily afford books!
I hope my great awe and esteem for the Chazon Ish is still crystal-clear.
This needs to be rewritten slowly with more and better examples, but “Perfect is the enemy of good“.
P. S., Here’s another Nafka Mina.