Does getting post-MBA MBB offer really depend on your experience prior to MBA?

For whatever reason, consulting firms have strict recruiting processes-if you miss the boat in undergrad, it's not that easy to simply lateral. That will require significant networking on your part, though I'm not sure how it works in your country. There are some roles that open up for experienced or niche backgrounds, but those are few and far between.

Most people who go to B-school do so with the intent of career switching/resetting, so they're able to get a 2nd (and possibly 3rd in a 2 year program) bite at the apple for MBA recruiting.

Your friend is mostly right about the stats that are required. These firms have to justify billing your services at a rate of hundreds of dollars per hour, so they tend to favor elite credentials for the most part. However, your creds won't mean dick if you can't crack a case.

For the record, I've seen people with your profile get MBB interviews, particularly for international locations. Apply up and down the tiers to be safe; plenty of people go to B-school w/ an "MBB or bust" attitude and get blown up when there are great opportunities at some of the other well regarded firms.