You have a valid question, but I’ve been an “official” Southern Baptist (member of SBC churches) for over 40 years, and there is a tried and true practice of NEVER purging the rolls...
Seems as soon as you do, Sunday School attendance begins to drop. Nobody can figure it out, but that’s what they say. Maybe it’s not even true, but nonetheless, any time somebody wants to “clean up” the membership list, it meets a lot of resistance.
Many times, people would rather go to a “feel good” church where sin is not preached, and God’s love is the only part of his character ever mentioned. Yes, He is a loving God, but also, He is a JUST God, and hates sin.
The SBC is a lot more conservative, and many (not all) SBC Pastors still talk about sin and the blood of Christ, and a lot of folks don’t want to hear that people will go to hell if they refuse Jesus. So, they head for a feel good church.
This is my fear. That Christ's work of redemption is no longer preached regularly and too many just want to hear pop music then have their ears tickled. I don't think an "altar call" is necessary each and every week but it ought to be at least once a month and the Lord's Supper should also be shared at least once a month with it's emphasis on Christ's sacrifice.
Christianity is exploding in parts of Asia and Africa. Many had never heard about Christ and He is being received openly in many areas where it was once forbidden. I sometimes wonder if God is preparing us for the final days when men of every race and culture will bow and confess Christ while many in Europe and North America who thought they knew Christ get left behind.
My church instituted 'Active' and 'Inactive' church rolls. That way, no one is dropped, but they also aren't counted on for participation in anything. I don't know which is the 'official' membership. I was on the 'Inactive' roll until we began attending regularly again last year, at which time my Presbyterian-raised wife joined and was dunked. Our Church is quite conservative in its doctrine, but not in things other than doctrine (we realize that instruments are not limited to piano and organ). The church also has a growing private school. However, even our attendance, which has grown for years, has leveled off, if not declined in the last year. Receipts are definitely down. Now, that may be a matter of economy rather than attendance, but times, they are a-changing.