First of all, I do not need links to find out what the position is. And my opinion is not based on my personal experience, but on the knowledge of immigration rules.
You cannot become an expert just because you submitted one personal application.
The information you provided is merely stating that for incountry applications, BRP is issued instead of sticker.
When someone arrived in UK, they get a visa which is a sticker. Do they come here and exchange that sticker for BRP as soon as they arrive? NO.
How on earth a valid visa which has been endorsed with a sticker will become useless because someone has made an application in UK?
Where did you read that stickers have become inoperative? Forget stickers, people have 20 years old ink stamps of their status on their expired passports and they still travel without a problem, including myself.
Because a sticker is valid till the validity shown on it. You can go in and out of UK with this sticker 100 times or a 1000 times.
Its only that when you extend your change your leave to remain in UK, that you get a BRP.
You do not seem like a person with any kind of legal knowledge, but for the benefits of others, I would like to clarify something else too.
Its not the sticker that is valuable, or the BRP. Its the leave to remain that has been granted that is important. Somebody could loose their passport, damage the sticker, and shred their BRP, they still are perfectly legal in UK as long as they have leave to remain. In theory, someone can turn up at a UK port, and forget their BRP back home. If the UKBA is statisfied with their identity, they will still be allowed entry into UK.