Much of the article has to do with how the Lord's Supper is viewed among Baptists, Calvinists, and Lutherans. At issue is whether the Lord's Supper is purely symbolic and done as remembrance (the traditional Baptist view) or whether it is a sacrament which conveys grace to the participant, which is the traditional Catholic view that was retained by the Reformers when the Protestant churches broke away from Catholicism.
The historic Baptist view seeks to be Biblical, placing most emphasis on Jesus words to 'do this in remembrance of me' (Luke 22:19) and Paul's statement that in partaking we proclaim the Lord's death till He comes and we do this in remembrance of Him (I Cor. 11:24-26). Paul even says it twice, that we do this in remembrance of Jesus. The verses where Jesus says 'this is my body' and 'this is my blood' are taken to be metaphorical, not literal. The sacramental view takes these verses literally, which leads to their teaching of 'transubstantiation' in which these elements become the actual body and blood of Jesus when believers receive the sacrament. Baptists call it 'The Lord's Supper' and do not call it 'Communion' to make it clear that they do not view it as a sacrament since the word 'Communion' (as well as 'Eucharist') are used by churches that view it as a sacrament.
The article linked above, and most Christian discussions of this topic, do not address the Jewish roots of the Lord's Supper. Jesus was observing a Passover Seder when He instituted it. It is clear that He was the fulfillment of Passover as the apostle Paul points out in I Cor. 5:7 ('Christ our Passover has been sacrificed'). Paul's stressing of doing this in remembrance of Christ's work at Passover accords well with the teaching about Passover when it was instituted in Exodus 12:14 where the Scripture says 'this day will be memorial to you'; clearly it is done in remembrance. Exodus also calls it a 'permanent ordinance' for the Jews, and Baptists also refer to the Lord's Supper as an 'ordinance' of the church, not a sacrament. Judaism did not have anything equivalent to sacraments (and still doesn't). However, there were consequences for not keeping commands like keeping the Passover. On that first Passover, failure to apply the blood meant death, and failure to keep it thereafter resulted in being 'cut off' from Israel (Num. 9:13). Paul also lays out consequences for not properly keeping the Lord's Supper in I Cor. 11:27-30 saying that improper observance has resulted in many of them in Corinth being sick or even dying! Paul's teaching about observing the Lord's Supper seems very much in accord with the Jewish ideas about keeping the Passover.
So it seems to me that it is very likely that both Jesus and the disciples would have viewed what Jesus taught in that last Passover before His crucifixion in a similar manner to the way they viewed Passover. It was instituted as a memorial, but with consequences for not being properly observed. In that way it was more than something that is 'merely symbolic' as Baptists are accused of teaching (and often do teach) but was not viewed as a sacrament. It was something in between those two extremes.
