Following up on the last post, we should ask, what does it mean that the Ibbur will become less during the stages before Moshiach's arrival, as it was during Galus Mitzraim?
Pirkei D'Rebbi Eliezer doesn't say that B'nei Yisrael did not practice Sod HaIbbur, it just says it was lessened. I would propose that the parallel between then and now could be the accuracy of our calendar.
Brief background: Our calendar is based on a 19 year cycle of lunar years, with 7 of these years having leap months. This is because 19 solar years is very close in length to 235 (19 * 12 + 7) lunar months. There is a set pattern of how we add leap months, and it created an accurate calendar, for its time, some 1600 years ago. Over time, however, the calendar has a drift, so that more and more years out of the 19 year cycle are too late.
In Rosh Hashanah 20b, Shmuel says that he can set up a calendar for the entire Golah. He doesn't mean the place; the calendar for Babylon and for Monsey are the same. Rather, Shmuel could make a calculation that would make a calendar that stays reasonably accurate until such time as a Sanhedrin could fix it. This is in our days.