Of course, in the period this article was written there was no such thing as the Reinheitsgebot. That term only came into use after WW I. And until 1908, the law on only brewing from malt, hops, water and yeast only applied to Bavaria, not the rest of Germany.
But it seems that things were more complicated than that. There were restrictions on the ingredients that could be used in beer in the whole of Germany.
"The use of substitutes in Bavaria is forbidden absolutely. There are two laws bearing on the question:—So you were only allowed to use substitutes if they didn't alter the nature of the beer. That doesn't really fit with what I've read about German rice beer, where the whole point of its use was to produce something that was lighter and more delicately flavoured.
(1) The Food and Drugs Act, and (2) The Malt Act.— Under the Food and Drugs Act it has been decided by, the Courts in a series of cases that the use of any material which tends to make the beer appear or actually be better or worse than is actually the case - viewed in the light of the fact that normal beer in Bavaria is by law and popular opinion regarded as a product obtained from malt, hops, and water, and subsequent fermentation — is not allowable.
The use of any material which alters the normal composition of a beer, tends to hide natural deficiencies, &c, is absolutely forbidden. The enalty is a fine of not more than 1,500 marks (£75), and six months’ imprisonment. Anyone concerned in the use or sale of such substances is subject to these penalties. It has been decided by the Courts that the use of caramel, bicarbonate of soda, tartaric acid, heading powder, grape-sugar (glucose), tannin, salicylic acid, &c., are illegal under the Food Act, and the persons concerned were condemned to various penalties. These cases occurred in the years 1885 and 1886. (Literature available.)
Under the Malt Act (a fiscal measure), the use of any material whatever in the manufacture of beer, except barley, malt, hops, water, and yeast is absolutely forbidden. Where the offencc can be brought either under the Food Act or the Malt Act, the former is always put in force, as the penalties are heavier.
In Germany generally (Imperial Law — Reichsgesetz) apart from Bavaria, the use of certain substitutes is allowed, but if these substitutes in any way alter the composition of the beer from the normal (i.e. a beer brewed from malt and hops alone), or tend to make a beer brewed from bad materials appear better than it really is, or worse, the use of such substitute is forbidden except on condition that such beers be qualified as "substitute ” beers, and given a special name clearly showing to the public that such beer is not a normal liquid. If a pure substitute be used and the normal composition of the beer be thereby in no way altered, the beer may be sold as “beer,” but it may not be sold in such a manner as to make the buyer believe that it is a beer brewed from "normal” materials alone. This applies also to wine. From this, and the decision of the Courts, it appears that there is a rigorous check on the use of impure substitutes and the abnormal use of even pure substitutes. In Bavaria it is held by the authorities that even a pure substitute must alter the actual character and properties of a beer, and, if this view be adopted by the Judges in Germany, it is evident that the existing Imperial Laws are sufficient to prohibit their use absolutely in the whole of Germany. This view has been adopted by some of the Courts. It is, therefore, incorrect to say that the use of substitutes is allowed in Germany, with the exception of Bavaria alone. As stated before, there are Imperial regulations as to analytical methods for detecting impurities and abnormal composition of wine, beers.
Apart from Chemical analysis, however, it was considered by all the authorities consulted in Munich that it would be quite impossible for a brewer to use substitutes without detection, and detection would mean his absolute ruin. Each brewer in Munich vies with the other in trying to produce a better beer; the quality of the beer is his chief advertisement. The manager of the largest brewery in Munich said to me, "If a brewer were detected in the use of substitutes — and he could not help bein detected — he would not only be ruined, but the people would try to lynch him as well.” This graphically expresses the very strong opinion on this question held in Bavaria."
"The Brewers' Journal, 1898", page 242.
The idea of having to name beer that wasn't brewed from malt and hops alone something else was floated in the UK around this time. Campaigners for "pure beer" wanted beer contained adjuncts or sugar to be clearly stated as doing so. They didn't get very far with that one.
I wonder if any Bavarian brewerss were ever lynched? It wouldn't surprise me. They are pretty crazy when it comes to beer down there.